Refrigeration apparatus

ABSTRACT

A refrigeration apparatus ( 1 ) is disclosed which is provided with multiple systems of utilization-side heat exchangers ( 20, 30, 40 ) and in which liquid-side interunit piping lines ( 53, 54, 55 ) are combined into a single liquid-side interunit piping line in multiple systems of liquid lines. When the refrigeration apparatus ( 1 ) provides space heating of 100% heat recovery without the use of an outdoor heat exchanger ( 15 ), the flow of refrigerant in a refrigerant circuit ( 50 ) is stabilized even when the temperature of outside air is low, thereby preventing the capacity to provide refrigeration from decreasing. In addition, in order to prevent shutdown of the refrigeration apparatus ( 1 ) due to malfunction, a liquid refrigerant inflow passageway ( 66 ) is connected to a heat source-side liquid pipe ( 62 ) of an outdoor unit ( 10 ), the heat source-side liquid pipe ( 62 ) being connected to an integrated liquid pipe ( 53 ) of the liquid-side interunit piping lines ( 53, 54, 55 ), and to an inlet port of the a receiver ( 17 ), and a switch valve (SV 1 ) capable of being on-off controlled is disposed in the liquid refrigerant inflow passageway ( 66 ).

TECHNICAL FIELD

The present invention relates in general to refrigeration apparatuses,and more particularly to refrigeration apparatuses which have aplurality of utilization-side heat exchangers for cold storage/freezestorage and air conditioning and which are operable in an operation modeof 100% heat recovery between/among each utilization-side heatexchanger.

BACKGROUND ART

In the past, a refrigeration apparatus of the type which performs arefrigeration cycle has been known in the art. Such a refrigerationapparatus has been used widely as an air conditioner for providingcooling/heating of an indoor space and as a cooler for providing coolingof a showcase compartment for food cold storage/freeze storage. Thistype of refrigeration apparatus includes a refrigeration apparatus whichprovides both air conditioning and cold storage/freeze storage (forexample, see Patent Document 1). This refrigeration apparatus isinstalled, for example, in a convenience store, and both store space airconditioning and showcase cooling are accomplished by installation ofthe single refrigeration apparatus.

The aforesaid refrigeration apparatus is configured as follows. Aplurality of utilization-side heat exchangers (heat exchangers for coldstorage, freeze storage, and air conditioning which are disposedrespectively in utilization-side units (cold storage showcases, freezestorage showcases, and air conditioning indoor units)) are connected, byliquid- and gas-side interunit piping lines, in parallel to a heatsource-side (outdoor) heat exchanger of a heat source-side (outdoor)unit which is installed outdoors.

Here, in the case where the refrigerant circuit has two systems, namelya first system-side circuit for cold storage/freeze storage and a secondsystem-side circuit for air conditioning, two interunit piping lines aregenerally arranged for each of a liquid and gas lines. On the otherhand, in order to reduce the number of interunit piping lines, it isproposed that liquid lines of two systems share a single liquid-sideinterunit piping line (see Patent Document 2).

More specifically, the refrigerant circuit of this apparatus isconfigured as shown in FIG. 10. Referring to FIG. 10, an outdoor unit(101), an indoor unit (102), a cold storage showcase (cold storage unit)(103), and a freeze storage showcase (freeze storage unit) (104) areshown. The outdoor unit (101) is provided with compression mechanisms(105, 106), an outdoor heat exchanger (107), an outdoor expansion valve(108), and a receiver (109). The indoor unit (102) is provided with anindoor heat exchanger (air conditioning heat exchanger) (110) and anindoor expansion valve (111). In addition, the cold storage showcase(103) is provided with a cold storage heat exchanger (112) and a coldstorage expansion valve (113). The freeze storage showcase (104) isprovided with a freeze storage heat exchanger (114), a freeze storageexpansion valve (115), and a booster compressor (116).

A refrigerant circuit (120) of the refrigeration apparatus includes afirst system-side circuit for cold storage/freeze storage and a secondsystem-side circuit for air conditioning. The first system-side circuitis configured such that refrigerant is circulated in one directionbetween the outdoor heat exchanger (107) and the cold and freeze storageheat exchangers (112, 114). The second system-side circuit is configuredsuch that refrigerant is circulated reversibly between the outdoor heatexchanger (107) and the indoor heat exchanger (110). And, a singleliquid-side interunit piping line (121) is shared between the liquidline of the first system-side circuit and the liquid line of the secondsystem-side circuit.

In the aforesaid refrigeration apparatus, it is possible to provideindoor space air conditioning and cooling of each showcase while theoutdoor heat exchanger (107) (installed outdoors) is used as a heatsource and, in addition, it is also possible to provide, without the useof the outdoor heat exchanger (107), heating and cold storage/freezestorage with 100% heat recovery in which the indoor heat exchanger (110)functions as a condenser and the cold and freeze storage heat exchangers(112, 114) function as evaporators.

Now, when performing a 100% heat recovery operation mode in therefrigerant circuit (120) provided with the single liquid-side interunitpiping line (121), discharged refrigerant from the compressionmechanisms (105, 106) is circulated in the refrigerant circuit (120)such that it is condensed in the indoor heat exchanger (110), evaporatedin the cold and freeze storage heat exchangers (112, 114), and drawnagain into the compression mechanisms (105, 106). Stated another way, atthis time, it is required that liquid refrigerant condensed in theindoor heat exchanger (110) is not allowed to flow in the direction ofthe heat source-side heat exchanger (107) from the receiver (109) but isto be introduced into the cold and freeze storage heat exchangers (112,114).

However, since the pressure in the receiver (109) drops, for example,when the temperature of outside air is low, the internal pressure of theliquid-side interunit piping line (121) likewise drops, and liquidrefrigerant exiting the indoor heat exchanger (110) is liable to flowinto the receiver (109) from the liquid-side interunit piping line(121), so that the volume of flow of refrigerant flowing to the cold andfreeze storage heat exchangers (112, 114) may run short. And, if thevolume of flow of refrigerant in the cold and freeze storage heatexchangers (112, 114) is insufficient, this reduces the capacity toprovide cooling of the compartment of each of the showcases (103, 104).

To cope with the above, in the refrigeration apparatus, a relief valve(117) is disposed in a refrigerant passageway extending from theliquid-side interunit piping line (121) to the receiver (109). Therelief valve (117) is a valve which is configured such that although itis placed in the opened state if the pressure of refrigerant in theliquid-side interunit piping line (121) increases to equal or exceed apredetermined value, it remains in the closed state until reaching thepredetermined value. And, by setting the working pressure of the reliefvalve (117) to a higher level than the pressure of the liquid-sideinterunit piping line (121) during the 100% heat recovery operationmode, the inflow of liquid refrigerant into the receiver (109) duringthe 100% heat recovery operation mode is prevented so that the flow ofrefrigerant in the refrigerant circuit (120) is stabilized even when thetemperature of outside air is low, thereby to prevent the capacity toprovide refrigeration from falling.

In addition, it is also possible for the refrigeration apparatus toperform a refrigerant cycle for space heating in which the outdoor heatexchanger (107) functions as an evaporator. However, at that time, therelief valve (117) is placed in the opened state because the suctionpressure of the compressor (106) is applied to the relief valve (117).Also note that during the cooling operation mode no refrigerant flowsthrough the passageway in which the relief valve (117) is disposed.

Patent Document 1: JP-A-2001-280749 Patent Document 2: JP-A-2005-134103DISCLOSURE OF THE INVENTION Problems that the Invention Seeks toOvercome

For example, in the case where a high heating capacity is requiredduring the 100% heat recovery operation mode in the aforesaid apparatus,it is conceivable that the amount of liquid refrigerant condensed in theindoor heat exchanger (100) exceeds the amount of refrigerant requiredin the cold and freeze storage heat exchangers (112, 114), leading tothe result that liquid refrigerant becomes excessive between the indoorheat exchanger (110) and the liquid-side interunit piping line (121). Onthe other hand, if at this time there is a request for increasing thecapacity to provide cooling storage/freezing storage, the operationcapacity of the compression mechanisms (105, 106) increases, and theamount of discharge gas refrigerant supplied to the indoor heatexchanger (110) will increase.

Even if the amount of discharge gas refrigerant is increased in the wayas described above when there is excess liquid refrigerant in the indoorheat exchanger (110) and the liquid-side interunit piping line (121),gas refrigerant will not readily flow through the indoor heat exchanger(110) because the liquid-side interunit piping line (121) is filled upwith liquid refrigerant, and the discharge pressure of the compressionmechanisms (105, 106) gradually increases. In this case, with theincrease in the discharge pressure, the liquid pressure of theliquid-side interunit piping line (121) also increases. If this liquidpressure exceeds the working pressure of the relief valve (117), therelief valve (117) is placed in the opened state, thereby making itpossible to permit escape of the liquid refrigerant to the receiver(109), and no operation problems will take place.

However, the discharge pressure of the compressors (105, 106) increasestoo much in some cases before the relief valve (117) is placed in theopened state, thereby causing a pressure switch (HPS) for high pressureprotection to activate. As a result, the compressors (105, 106) stopoperating and the apparatus may stop operating due to malfunction.

With the above problems in mind, the present invention was made.Accordingly, an object of the present invention is to prevent thecapability to provide refrigeration from falling by stabilizing the flowof refrigerant in a refrigerant circuit even when the temperature ofoutside air is low, and to avoid shutdown due to malfunction, at thetime when providing heating of 100% heat recovery without the use of anoutdoor heat exchanger in a refrigeration apparatus which is providedwith plural systems of utilization-side heat exchangers and in which asingle liquid-side interunit piping line is shared among a plurality ofliquid lines.

Means for Overcoming the Problems

The present invention provides, as a first aspect, a refrigerationapparatus comprising: a heat source-side unit (10) including acompression mechanism (11D, 11E), a heat source-side heat exchanger(15), and a receiver (17); a first utilization-side unit (30, 40)including a first utilization-side heat exchanger (31, 41); a secondutilization-side unit (20) including a second utilization-side heatexchanger (21); and a gas-side interunit piping line (51, 52) and aliquid-side interunit piping line (53, 54, 55) which establishconnections between each unit (10, 20, 30, 40) to thereby constitute arefrigerant circuit (50), wherein the gas-side interunit piping line(51, 52) includes: a first gas-side interunit piping line (51) which isconnected to the heat source-side unit (10) and to the firstutilization-side unit (30, 40); and a second gas-side interunit pipingline (52) which is connected to the heat source-side unit (10) and tothe second utilization-side unit (20), and wherein the liquid-sideinterunit piping line (53, 54, 55) includes: an integrated liquid pipe(53) which is connected to the heat source-side unit (10); a firstbranch liquid pipe (54) which diverges from the integrated liquid pipe(53) to connect to the first utilization-side unit (30, 40); and asecond branch liquid pipe (55) which diverges from the integrated liquidpipe (53) to connect to the second utilization-side unit (20).

And the refrigeration apparatus of the first aspect is characterized inthat the refrigeration apparatus further comprises: a liquid refrigerantinflow passageway (66) which is connected to a heat source-side liquidpipe (62) of the heat source-side unit (10), the heat source-side liquidpipe (62) being connected to the integrated liquid pipe (53) of theliquid-side interunit piping line (53, 54, 55), and to an inlet port ofthe receiver (17); and a switch valve (SV1) which is disposed in theliquid refrigerant inflow passageway (66) and which is capable of beingon-off controlled.

In the first aspect of the present invention, during the 100% heatrecovery operation mode in which the second utilization-side heatexchanger (21) functions as a condenser while the first utilization-sideheat exchanger (31, 41) functions as an evaporator, refrigerant flowssequentially through the compression mechanism (11D, 11E), through thesecond gas-side interunit piping line (52), through the secondutilization-side heat exchanger (21), through the second branch liquidpipe (55), through the first branch liquid pipe (54), through the firstutilization-side heat exchanger (31, 41), and through the first gas-sideinterunit piping line (51). At this time, if the switch valve (SV1) isplaced in the closed state, no refrigerant flows towards any of thefirst branch liquid pipe (54), the integrated liquid pipe (53), the heatsource-side liquid pipe (62), the liquid refrigerant inflow passageway(66), and the receiver (17). Accordingly, the refrigeration apparatusoperates wherein the quantity of heat of condensation of the secondutilization-side heat exchanger (21) and the quantity of heat ofevaporation of the first utilization-side heat exchanger (31, 41) are inbalance with each other.

On the other hand, if the operation capacity of the compressionmechanism (11D, 11E) is increased when there is excess refrigerant inthe second utilization-side heat exchanger (21) and the liquid-sideinterunit piping line (53, 54, 55), it is best to perform an operationthat places the switch valve (SV1) in the opened state. When this isdone, it becomes possible to permit escape of the liquid refrigerantcongested in the second utilization-side heat exchanger (21) and theliquid-side interunit piping line (53, 54, 55) to the receiver (17) fromthe first branch liquid pipe (54) by way of the integrated liquid pipe(53), the heat source-side liquid pipe (62), and the liquid refrigerantinflow passageway (66), whereby the discharge pressure of thecompression mechanism (11D, 11E) is prevented from increasing too much.

The present invention provides, as a second aspect according to thefirst aspect, a refrigeration apparatus which is characterized in that aplurality of the second utilization-side units (20) are connected inparallel to the heat source-side unit (10).

In the second aspect of the present invention, when, during the 100%heat recovery operation mode, a selected one of the secondutilization-side units (20) is placed in the thermo-off state (which isa state that performs an air supply operation in which refrigeranteither stops circulating through the second utilization-side heatexchanger (21) or is allowed to flow therethrough, but in very smallamount), the expansion mechanism which is connected to the secondutilization-side unit (20) is either placed in the fully closed state oris set such that although it is opened the degree of opening thereof isvery small. At this time, since the rest of the second utilization-sideunits (20) continue to provide heating (space heating), dischargedrefrigerant from the compression mechanism (11D, 11E) is supplied alsoto the second utilization-side heat exchanger (21) placed in thethermo-off state. However, little refrigerant flows in the thermo-offed,second utilization-side heat exchanger (21) and, as a result,refrigerant is rapidly accumulated therein.

At this time, if there is a request to increase the refrigerationcapacity of the first utilization-side heat exchanger (31, 41), anoperation to increase the capacity of the compression mechanism (11D,11E) is performed. As a result, the discharge pressure of thecompression mechanism (11D, 11E) increases, so that if the switch valve(SV1) of the liquid refrigerant inflow passageway (66) continues toremain in the closed state, this may lead to the possibility that thedischarge pressure of the compression mechanism (11D, 11E) increases toomuch, but nonetheless an operation to place the switch valve (SV1) inthe opened state is performed in the second aspect of the presentinvention, thereby permitting escape of the liquid refrigerant to thereceiver (17), and the discharge pressure of the compression mechanism(11D, 11E) is prevented from increasing too much.

The present invention provides, as a third aspect according to eitherthe first or the second aspect, a refrigeration apparatus which ischaracterized in that the first utilization-side unit (30, 40) is acooling machine for providing compartment cooling and the heatsource-side unit (10) and the first utilization-side unit (30, 40)together constitute a first system-side circuit (50A) in whichrefrigerant is circulated in one direction; and that the secondutilization-side unit (20) is an air conditioning machine for providingindoor air conditioning and the heat source-side unit (10) and thesecond utilization-side unit (20) together constitute a secondsystem-side circuit (50B) in which refrigerant is reversibly circulated.

In the third aspect of the present invention, the first utilization-sideheat exchanger (31, 41) in the first system-side circuit (50A) providescompartment cooling while the second utilization-side heat exchanger(21) in the second system-side circuit (50B) provides indoor airconditioning (space cooling/heating). In this case, it is possible toprevent the discharge pressure of the compression mechanism (11D, 11E)from increasing too much by placing the switch valve (SV1) in the openedstate, even if during the 100% heat recovery operation mode in which thesecond utilization-side heat exchanger (21) functions as a condenserwhile the first utilization-side heat exchanger (31, 41) functions as anevaporator, the operation capacity of the compression mechanism (11D,11E) is increased when there is excess refrigerant in the secondutilization-side heat exchanger (21) and the liquid-side interunitpiping line (53, 54, 55).

The present invention provides, as a fourth aspect according to any oneof the first to third aspects, a refrigeration apparatus which ischaracterized in that the refrigeration apparatus further comprises acontrol means (95) for performing on-off control of the switch valve(SV1) in response to the operation state.

In the fourth aspect of the present invention, the switch valve (SV1) isplaced in the opened state, for example, when the discharge pressure ofthe compression mechanism (11D, 11E) increases or when although there isno increase in the discharge pressure, there is an accumulation ofliquid refrigerant between the second utilization-side heat exchanger(21) and the liquid-side interunit piping line (53, 54, 55) during the100% heat recovery operation mode. On the other hand, the switch valve(SV1) is placed in the closed state when the second system-side circuit(50B) provides cooling of the utilization side (for example, when thesecond system-side circuit (50B) is a circuit for air conditioning andis in operation to provide space cooling) or when the compressionmechanism (11D, 11E) is placed at rest. In addition, even in the casewhere the second utilization-side heat exchanger (21) functions as acondenser, an operation to place the switch valve (SV1) in the openedstate is performed in such an operation state that the heat source-sideheat exchanger (15) is employed as an evaporator.

The present invention provides, as a fifth aspect according to thefourth aspect, a refrigeration apparatus which is characterized in thatthe control means (95) is configured such that in an operation state inwhich the second utilization-side heat exchanger (21) functions as acondenser while the first utilization-side heat exchanger (31, 41)functions as an evaporator, the switch valve (SV1) is placed either inthe closed state if the discharge pressure of the compression mechanism(11D, 11E) is below a predetermined value or in the opened state if thedischarge pressure of the compression mechanism (11D, 11E) increases toequal or exceed the predetermined value.

In the fifth aspect of the present invention, during the 100% heatrecovery operation mode in which the second utilization-side heatexchanger (21) functions as a condenser while the first utilization-sideheat exchanger (31, 41) functions as an evaporator, the switch valve(SV1) is placed in the closed state if the discharge pressure of thecompression mechanism (11D, 11E) is below the predetermined value.Accordingly, the refrigeration apparatus operates wherein the quantityof heat of condensation of the second utilization-side heat exchanger(21) and the quantity of heat of evaporation of the firstutilization-side heat exchanger (31, 41) are in balance with each other.On the other hand, the switch valve (SV1) is placed in the opened stateif the discharge pressure of the compression mechanism (11D, 11E)reaches the predetermined value or above, thereby permitting escape ofthe high pressure refrigerant between the second utilization-side heatexchanger (21) and the liquid-side interunit piping line (53, 54, 55)into the receiver (17). By setting the set pressure of the switch valve(SV1) at which it is placed in the opened state to fall below theworking pressure of a pressure switch for high pressure protection, itbecomes possible to prevent the discharge pressure of the compressionmechanism (11D, 11E) from increasing too much.

The present invention provides, as a sixth aspect according to thefourth aspect, a refrigeration apparatus which is characterized in thatthe control means (95) is configured such that in an operation state inwhich the second utilization-side heat exchanger (21) functions as acondenser while the first utilization-side heat exchanger (31, 41)functions as an evaporator, the switch valve (SV1) is placed either inthe closed state if the amount of liquid refrigerant accumulated in thesecond utilization-side heat exchanger (21) and the liquid-sideinterunit piping line (53, 54, 55) is below a predetermined value or inthe opened state if it is estimated that the liquid refrigerant amountaccumulated reaches the predetermined value or above. In this case, itis possible to estimate that liquid refrigerant is accumulated in thesecond utilization-side heat exchanger (21) and the liquid-sideinterunit piping line (53, 54, 55) from the fact that the value,detected by a sensor for detection of the temperature of gas refrigerantin the second utilization-side heat exchanger (21) during the 100% heatrecovery operation mode, approaches the saturated temperaturecorresponding to the pressure.

In the sixth aspect of the present invention, during the 100% heatrecovery operation mode in which the second utilization-side heatexchanger (21) functions as a condenser while the first utilization-sideheat exchanger (31, 41) functions as an evaporator, the switch valve(SV1) is placed in the closed state if the amount of liquid refrigerantaccumulated in the second utilization-side heat exchanger (21) and theliquid-side interunit piping line (53, 54, 55) is below thepredetermined value. Accordingly, the refrigeration apparatus operateswherein the quantity of heat of condensation of the secondutilization-side heat exchanger (21) and the quantity of heat ofevaporation of the first utilization-side heat exchanger (31, 41) are inbalance with each other. On the other hand, the switch valve (SV1) isplaced in the opened state if it is estimated that the liquidrefrigerant amount accumulated reaches the predetermined value or above,thereby permitting escape of the high pressure refrigerant between thesecond utilization-side heat exchanger (21) and the liquid-sideinterunit piping line (53, 54, 55) into the receiver (17). Thistherefore makes it possible to prevent excess accumulation of liquidrefrigerant in the second utilization-side heat exchanger (21) and theliquid-side interunit piping line (53, 54, 55).

The present invention provides, as a seventh aspect according to thefourth aspect, a refrigeration apparatus which is characterized in thatthe control means (95) is configured such that in an operation state inwhich the second utilization-side heat exchanger (21) functions as acondenser while the first utilization-side heat exchanger (31, 41)functions as an evaporator, the switch valve (SV1) is placed either inthe closed state if the temperature of liquid refrigerant in the secondutilization-side heat exchanger (21) is below the predetermined value orin the opened state if the liquid refrigerant temperature increases toequal or exceed the predetermined value.

In the seventh aspect of the present invention, during the 100% heatrecovery operation mode in which the second utilization-side heatexchanger (21) functions as a condenser while the first utilization-sideheat exchanger (31, 41) functions as an evaporator, the switch valve(SV1) is placed in the closed state if the temperature of liquidrefrigerant in the second utilization-side heat exchanger (21) is belowa predetermined value. Accordingly, the refrigeration apparatus operateswherein the quantity of heat of condensation of the secondutilization-side heat exchanger (21) and the quantity of heat ofevaporation of the first utilization-side heat exchanger (31, 41) are inbalance with each other. On the other hand, the switch valve (SV1) isplaced in the opened state if the liquid refrigerant temperatureincreases to equal or exceed the predetermined value, thereby permittingescape of the high pressure refrigerant between the secondutilization-side heat exchanger (21) and the liquid-side interunitpiping line (53, 54, 55) into the receiver (17). By setting the setpressure of the switch valve (SV1) at which it is placed in the openedstate to fall below the working pressure of a pressure switch for highpressure protection, it becomes possible to prevent the dischargepressure of the compression mechanism (11D, 11E) from increasing toomuch.

The present invention provides, as an eighth aspect according to thefourth aspect, a refrigeration apparatus which is characterized in thatthe control means (95) is configured such that in an operation state inwhich the second utilization-side heat exchanger (21) functions as acondenser while the first utilization-side heat exchanger (31, 41)functions as an evaporator, the switch valve (SV1) is placed either inthe closed state if the pressure of liquid refrigerant in theliquid-side interunit piping line (53, 54, 55) is below a predeterminedvalue or in the opened state if the liquid refrigerant pressureincreases to equal or exceed the predetermined value.

In the eighth aspect of the present invention, during the 100% heatrecovery operation mode in which the second utilization-side heatexchanger (21) functions as a condenser while the first utilization-sideheat exchanger (31, 41) functions as an evaporator, the switch valve(SV1) is placed in the closed state if the pressure of liquidrefrigerant in the liquid-side interunit piping line (53, 54, 55) isbelow the predetermined value. Accordingly, the refrigeration apparatusoperates wherein the quantity of heat of condensation of the secondutilization-side heat exchanger (21) and the quantity of heat ofevaporation of the first utilization-side heat exchanger (31, 41) are inbalance with each other. On the other hand, the switch valve (SV1) isplaced in the opened state if the liquid refrigerant pressure increasesto equal or exceed the predetermined value, thereby permitting escape ofthe high pressure refrigerant in the liquid-side interunit piping line(53, 54, 55) into the receiver (17). By setting the set pressure of theswitch valve (SV1) at which it is placed in the opened state to fallbelow the working pressure of a pressure switch for high pressureprotection, it becomes possible to prevent the discharge pressure of thecompression mechanism (11D, 11E) from increasing too much.

ADVANTAGEOUS EFFECTS OF THE INVENTION

In the refrigeration apparatus of the present invention capable ofoperating, without the use of the heat source-side heat exchanger (15),in a 100% heat recovery operation mode in which the secondutilization-side heat exchanger (21) and the first utilization-side heatexchanger (31, 41) function respectively as a condenser and as anevaporator, the liquid refrigerant inflow passageway (66) is connectedto the heat source-side liquid pipe (62) of the heat source-side unit(10), the heat source-side liquid pipe (62) being connected to theintegrated liquid pipe (53) of the liquid-side interunit piping line(53, 54, 55), and to the inlet port of the receiver (17) and the switchvalve (SV1) capable of being on-off controlled is disposed in the liquidrefrigerant inflow passageway (66). Therefore, by performing such a 100%heat recovery operation mode with the switch valve (SV1) placed in theclosed state, the refrigeration apparatus operates wherein the quantityof heat of condensation of the second utilization-side heat exchanger(21) and the quantity of heat of evaporation of the firstutilization-side heat exchanger (31, 41) are in balance with each other.

On the other hand, if the operation capacity of the compressionmechanism (11D, 11E) is increased when there is excess refrigerant inthe second utilization-side heat exchanger (21) and the liquid-sideinterunit piping line (53, 54, 55), an operation to place the switchvalve (SV1) in the opened state is performed, thereby permitting escapeof the liquid refrigerant accumulated in the second utilization-sideheat exchanger (21) and the liquid-side interunit piping line (53, 54,55) to the receiver (17) from the first branch liquid pipe (54) by wayof the integrated liquid pipe (53), the heat source-side liquid pipe(62), and the liquid refrigerant inflow passageway (66). Therefore, itbecomes possible to prevent the high pressure of the compressionmechanism (11D, 11E) from increasing too much. Accordingly, if it isarranged such that prior to activation of the pressure switch (HPS) forhigh pressure protection the switch valve (SV1) is placed in the openedstate, this makes it possible to prevent the refrigeration apparatusfrom malfunctioning to stop operating due to shutdown of the compressionmechanism (11D, 11E).

In the case where the second utilization-side units (20) are connectedin parallel to the heat source-side unit (10), the discharge pressure ofthe compression mechanism (11D, 11E) tends to increase if there is asecond utilization-side unit (20) that is placed in the thermo-off stateand in addition the refrigeration apparatus tends to stop operatingbecause of activation of the pressure switch for high pressureprotection. However, according to the second aspect of the presentinvention, placing the switch valve (SV1) in the opened state prior toactivation of the pressure switch may ensure that the malfunction of therefrigeration apparatus is prevented from occurring.

In the refrigeration apparatus according to the third aspect of thepresent invention having the first system-side circuit (50A) in whichrefrigerant is circulated between the heat source-side unit (10) and thefirst utilization-side unit (30, 40) in one direction to thereby providecompartment cooling and the second system-side circuit (50A) in whichrefrigerant is circulated reversibly between the heat source-side unit(10) and the second utilization-side unit (20) to thereby provide indoorair conditioning, the discharge pressure of the compression mechanism(11D, 11E) is prevented from increasing too much by placing the switchvalve (SV1) in the opened state during the 100% heat recovery operationmode in which the second utilization-side heat exchanger (21) and thefirst utilization-side heat exchanger (31, 41) function, respectively,as a condenser and as an evaporator, even if the operation capacity ofthe compression mechanism (11D, 11E) is increased when there is excessrefrigerant in the second utilization-side heat exchanger (21) and theliquid-side interunit piping line (53, 54, 55). Accordingly, as in thefirst and second aspects of the present invention, it is ensured thatthe refrigeration apparatus is prevented from malfunction.

According to the fourth aspect of the present invention, by virtue ofthe provision of the control means (95) capable of on-off control of theswitch valve (SV1) in response to the operation state, it becomespossible to prevent the occurrence of operation problems in the 100%heat recovery operation mode or other operation mode.

According to the fifth aspect of the present invention, in the operationstate in which the second utilization-side heat exchanger (21) and thefirst utilization-side heat exchanger (31, 41) function, respectively,as a condenser and an evaporator, the switch valve (SV1) is placed inthe closed state if the discharge pressure of the compression mechanism(11D, 11E) is below the predetermined value while on the other hand theswitch valve (SV1) is placed in the opened state if the dischargepressure of the compression mechanism (11D, 11E) increases to equal orexceed the predetermined value. Therefore, during the 100% heat recoveryoperation mode, the switch valve (SV1) is placed in the closed stateunder normal conditions whereby the refrigeration apparatus operateswherein the quantity of heat of condensation of the secondutilization-side heat exchanger (21) and the quantity of heat ofevaporation of the first utilization-side heat exchanger (31, 41) are inbalance with each other. On the other hand, since it is possible topermit escape of high pressure refrigerant between the secondutilization-side heat exchanger (21) and the liquid-side interunitpiping line (53, 54, 55) into the receiver (17) by placing the switchvalve (SV1) in the opened state if the discharge pressure of thecompression mechanism (11D, 11E) reaches the predetermined value orabove, it becomes possible to prevent the problem that causes therefrigeration apparatus to stop operating by setting the set pressure ofthe switch valve (SV1) at which it is placed in the opened state to fallbelow the working pressure of the pressure switch for high pressureprotection.

According to the sixth aspect of the present invention, in the operationstate in which the second utilization-side heat exchanger (21) and thefirst utilization-side heat exchanger (31, 41) function, respectively,as a condenser and an evaporator, the switch valve (SV1) is placed inthe closed state if the amount of liquid refrigerant accumulated in thesecond utilization-side heat exchanger (21) and the liquid-sideinterunit piping line (53, 54, 55) is below the predetermined valuewhile on the other hand the switch valve (SV1) is placed in the openedstate if it is estimated that the liquid refrigerant amount accumulatedreaches the predetermined value or above. Therefore, during the 100%heat recovery operation mode, the switch valve (SV1) is placed in theclosed state under normal conditions whereby the refrigeration apparatusoperates wherein the quantity of heat of condensation of the secondutilization-side heat exchanger (21) and the quantity of heat ofevaporation of the first utilization-side heat exchanger (31, 41) are inbalance with each other. On the other hand, it is possible to permitescape of high pressure refrigerant between the second utilization-sideheat exchanger (21) and the liquid-side interunit piping line (53, 54,55) into the receiver (17) by placing the switch valve (SV1) in theopened state if it is estimated that the liquid refrigerant amountaccumulated reaches the predetermined value or above. This thereforemakes it possible to prevent excess accumulation of liquid refrigerantin the second utilization-side heat exchanger (21) and the liquid-sideinterunit piping line (53, 54, 55), and it becomes also possible toprevent the refrigeration apparatus from malfunctioning to stopoperating due to the discharge pressure of the compression mechanism(11D, 11E) increasing too much.

According to the seventh aspect of the present invention, in theoperation state in which the second utilization-side heat exchanger (21)and the first utilization-side heat exchanger (31, 41) function,respectively, as a condenser and an evaporator, the switch valve (SV1)is placed in the closed state if the temperature of liquid refrigerantin the second utilization-side heat exchanger (21) is below thepredetermined value while on the other hand the switch valve (SV1) isplaced in the opened state if the liquid refrigerant temperatureincreases to equal or exceed the predetermined value. Therefore, duringthe 100% heat recovery operation mode, the switch valve (SV1) is placedin the closed state under normal conditions whereby the refrigerationapparatus operates wherein the quantity of heat of condensation of thesecond utilization-side heat exchanger (21) and the quantity of heat ofevaporation of the first utilization-side heat exchanger (31, 41) are inbalance with each other. On the other hand, since it is possible topermit escape of high pressure refrigerant between the secondutilization-side heat exchanger (21) and the liquid-side interunitpiping line (53, 54, 55) into the receiver (17) by placing the switchvalve (SV1) in the opened state if the liquid refrigerant temperatureincreases to equal or exceed the predetermined value, it becomespossible to prevent the problem that causes the compression mechanism(11D, 11E) to stop operating by setting the pressure derived from theset temperature of the switch valve (SV1) at which it is placed in theopened state to fall below the working pressure of the pressure switchfor high pressure protection.

According to the eighth aspect of the present invention, in theoperation state in which the second utilization-side heat exchanger (21)and the first utilization-side heat exchanger (31, 41) function,respectively, as a condenser and an evaporator, the switch valve (SV1)is placed in the closed state if the pressure of liquid refrigerant inthe liquid-side interunit piping line (53, 54, 55) is below thepredetermined value while on the other hand the switch valve (SV1) isplaced in the opened state if the liquid refrigerant pressure increasesto equal or exceed the predetermined value. Therefore, during the 100%heat recovery operation mode, the switch valve (SV1) is placed in theclosed state under normal conditions whereby the refrigeration apparatusoperates wherein the quantity of heat of condensation of the secondutilization-side heat exchanger (21) and the quantity of heat ofevaporation of the first utilization-side heat exchanger (31, 41) are inbalance with each other. On the other hand, since it is possible topermit escape of high pressure refrigerant in the liquid-side interunitpiping line (53, 54, 55) into the receiver (17) by placing the switchvalve (SV1) in the opened state if the liquid refrigerant pressureincreases to equal or exceed the predetermined value, it becomespossible to prevent the problem that causes the compression mechanism(11D, 11E) to stop operating by setting the pressure derived from theset temperature of the switch valve (SV1) at which it is placed in theopened state to fall below the working pressure of the pressure switchfor high pressure protection.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings:

FIG. 1 is a refrigerant circuit diagram of a refrigeration apparatusaccording to an embodiment of the present invention;

FIG. 2 is a refrigerant circuit diagram illustrating a cooling operationmode in the embodiment;

FIG. 3 is a refrigerant circuit diagram illustrating a refrigerationoperation mode in the embodiment;

FIG. 4 is a refrigerant circuit diagram illustrating a firstcooling/refrigeration operation mode in the embodiment;

FIG. 5 is a refrigerant circuit diagram illustrating a secondcooling/refrigeration operation mode in the embodiment;

FIG. 6 is a refrigerant circuit diagram illustrating a heating operationmode in the embodiment;

FIG. 7 is a refrigerant circuit diagram illustrating a firstheating/refrigeration operation mode in the embodiment;

FIG. 8 is a refrigerant circuit diagram illustrating a secondheating/refrigeration operation mode in the embodiment;

FIG. 9 is a refrigerant circuit diagram illustrating a thirdheating/refrigeration operation mode in the embodiment; and

FIG. 10 is a refrigerant circuit diagram of a conventional refrigerationapparatus.

DESCRIPTION OF THE REFERENCE NUMERALS

-   1: refrigeration apparatus-   10: outdoor unit (heat source-side unit)-   11D: compression mechanism-   11E: compression mechanism-   15: outdoor heat exchanger (heat source-side heat exchanger)-   17: receiver-   20: indoor unit (second utilization-side unit)-   21: indoor heat exchanger (second utilization-side heat exchanger)-   30: cold storage unit (first utilization-side unit)-   31: cold storage heat exchanger (first utilization-side heat    exchanger)-   40: freeze storage unit (first utilization-side unit)-   41: freeze storage heat exchanger (first utilization-side heat    exchanger)-   50: refrigerant circuit-   50A: first system-side circuit-   50B: second system-side circuit-   51: first gas-side interunit piping line (gas-side interunit piping    line)-   52: second gas-side interunit piping line (gas-side interunit piping    line)-   53: integrated liquid pipe (liquid-side interunit piping line)-   54: first branch liquid pipe (liquid-side interunit piping line)-   55: second branch liquid pipe (liquid-side interunit piping line)-   62: outdoor liquid pipe (heat source-side liquid pipe)-   66: liquid refrigerant inflow passageway-   95: control means-   SV1: solenoid valve (switch valve)

BEST MODE FOR CARRYING OUT THE INVENTION

In the following, preferred embodiments of the present invention will bedescribed in detail with reference to the drawings.

FIG. 1 is a refrigerant circuit diagram of a refrigeration apparatus (1)according to an embodiment of the present invention. The refrigerationapparatus (1) is installed, for example, in a convenience store andprovides cooling of a showcase used for cold storage, cooling of ashowcase used for freeze storage, and cooling/heating of the storespace.

The refrigeration apparatus (1) includes these units: an outdoor unit(heat source-side unit) (10), an indoor unit (second utilization-sideunit) (20), a cold storage unit (first utilization-side unit) (30), anda freeze storage unit (first utilization-side unit) (40). These units(10, 20, 30, 40) are connected by a gas-side interunit piping line (51,52) and a liquid-side interunit piping line (53, 54, 55) to constitute arefrigerant circuit (50) in which a vapor compression refrigerationcycle is performed.

The gas-side interunit piping line (51, 52) is made up of a firstgas-side interunit piping line (low pressure gas pipe) (51) and a secondgas-side interunit piping line (52). The first gas-side interunit pipingline (51) is connected to the outdoor unit (10), the cold storage unit(30), and the freeze storage unit (40). The second gas-side interunitpiping line (52) is connected to the outdoor unit (10) and the indoorunit (20). On the other hand, the liquid-side interunit piping line (53,54, 55) is made up of an integrated liquid pipe (53), a first branchliquid pipe (54), and a second branch liquid pipe (55). The integratedliquid pipe (53) is connected to the outdoor unit (10). The first branchliquid pipe (54) is a branch pipe diverged from the integrated liquidpipe (53) for connection to the cold storage unit (30) and the freezestorage unit (40). The second branch liquid pipe (55) is also a branchpipe diverged from the integrated liquid pipe (53) for connection to theindoor unit (20). Also note that the first branch liquid pipe (54) ismade up of a cold storage-side first branch liquid pipe (54 a) on theside of the cold storage unit (30) and a freeze storage-side firstbranch liquid pipe (54 b) on the side of the freeze storage unit (40).In the present embodiment, the integrated liquid pipe (53) which is aportion of the liquid-side interunit piping line (53, 54, 55) on theside of the outdoor unit (10) is shared between the indoor unit (20) andthe cold and freeze storage units (30, 40), in other words, the presentembodiment employs an interunit piping line configuration of thethree-pipe system.

The indoor unit (20) is configured switchably between a coolingoperation mode and a heating operation mode and is installed, forexample, in a store selling space or the like. In addition, the coldstorage unit (30) is placed in a showcase used for cold storage andprovides cooling of compartment air in the cold storage showcase. Thefreeze storage unit (40) is placed in a showcase used for freeze storageand provides cooling of compartment air in the freeze storage showcase.In the present embodiment, two indoor units (20) are connected inparallel, eight cold storage units (30) are connected in parallel, and asingle freeze storage unit (40) is connected. However, for the sake ofsimplicity there are only shown in the figure one of the two indoorunits (20), one of the eight cold storage units (30), and the one freezestorage unit (40).

And, the refrigerant circuit (50) includes a first system-side circuit(50A) used to provide cold/freeze storage and a second system-sidecircuit (50B) used to provide air conditioning. The first system-sidecircuit (50A) is made up of the outdoor unit (10) which is a heatsource-side unit, the cold storage unit (30) which is a firstutilization-side unit, and the freeze storage unit (40) which is a firstutilization-side unit, and refrigerant is circulated in one directiontherein. On the other hand, the second system-side circuit (50B) is madeup of the outdoor unit (10) which is a heat source-side unit and theindoor unit (20) which is a second utilization-side unit, andrefrigerant is circulated reversibly therein.

Outdoor Unit

The outdoor unit (10) is provided with an inverter compressor (11A) as afirst compressor, a first non-inverter compressor (11B) as a secondcompressor, and a second non-inverter compressor (11C) as a thirdcompressor. In addition to these compressors, the outdoor unit (10)further includes a first four-way valve (12), a second four-way valve(13), a third four-way valve (14), and an outdoor heat exchanger (15)which is a heat source-side heat exchanger. Also note that the outdoorheat exchanger (15) is, for example, a fin and tube heat exchanger ofthe cross fin type, and an outdoor fan (16) which is a heat source fanis disposed in vicinity to the outdoor heat exchanger (15).

The compressors (11A, 11B, 11C) are each formed, for example, by ahermetic, high pressure dome type scroll compressor. The invertercompressor (11A) is a variable capacity compressor the capacity of whichcan be gradually or continuously variable by inverter control of anelectric motor. Each of the first and second non-inverter compressors(11B, 11C) is a fixed displacement compressor which is driven by anelectric motor constantly at a fixed speed of rotation.

The inverter compressor (11A), the first non-inverter compressor (11B),and the second non-inverter compressor (11C) together constitute acompression mechanism (11D, 11E) of the refrigeration apparatus (1). Thecompression mechanism (11D, 11E) is made up of a compression mechanism(11D) of a first system and a compression mechanism (11E) of a secondsystem. More specifically, the compression mechanism (11D, 11E) when inoperation is configured as follows. On one hand, the inverter compressor(11A) and the first non-inverter compressor (11B) together constitutethe compression mechanism (11D) of the first system while the secondnon-inverter compressor (11C) alone constitutes the compressionmechanism (11E) of the second system. On the other hand, the invertercompressor (11A) alone constitutes the compression mechanism (11D) ofthe first system while the first non-inverter compressor (11B) and thesecond non-inverter compressor (11C) together constitute the compressionmechanism (11E) of the second system. Stated another way, the invertercompressor (11A) is used fixedly by the first system-side circuit (50A)for cold/freeze storage and the second non-inverter compressor (11 c) isused fixedly by the second system side circuit (50B) for airconditioning while the first non-inverter compressor (11B) can be usedselectively by either the first system-side circuit (50A) or the secondsystem-side circuit (50B).

The inverter compressor (11A), the first non-inverter compressor (11B),and the second non-inverter compressor (11C) have respective dischargepipes (56 a, 56 b, 56 c) which are connected to a single high pressuregas pipe (discharge piping line) (57). The discharge pipe (56 b) of thefirst non-inverter compressor (11B) is provided with a check valve(CV1). The discharge pipe (56 c) of the second non-inverter compressor(11C) is provided with a check valve (CV2).

The high pressure gas pipe (57) is connected to a first port (P1) of thefirst four-way valve (12). The gas-side end of the outdoor heatexchanger (15) is connected to a second port (P2) of the first four-wayvalve (12) by an outdoor first gas pipe (58 a). The second gas-sideinterunit piping line (52) is connected through an outdoor second gaspipe (58 b) to a third port (P3) of the first four-way valve (12). Afourth port (P4) of the first four-way valve (12) is connected to thesecond four-way valve (13).

A first port (P1) of the second four-way valve (13) is connected to thedischarge pipe (56 c) of the second non-inverter compressor (11C) by anauxiliary gas pipe (59). A second port (P2) of the second four-way valve(13) is a closed port, in other word the second port (P2) is blocked. Athird port (P3) of the second four-way valve (13) is connected to thefourth port (P4) of the first four-way valve (12) by a connection pipe(60). In addition, a suction pipe (61 c) of the second non-invertercompressor (11C) is connected to a fourth port (P4) of the secondfour-way valve (13). Since the second port (P2) of the second four-wayvalve (13) is a closed port, this may allow use of a three-way valve asa substitute for the second four-way valve (13).

The first four-way valve (12) is configured such that it is switchablebetween (i) a first state (see solid line representation in the figure)that allows fluid communication between the first port (P1) and thesecond port (P2), and between the third port (P3) and the fourth port(P4) and (ii) a second state (see broken line representation in thefigure) that allows fluid communication between the first port (P1) andthe third port (P3), and between the second port (P2) and the fourthport (P4).

Likewise, the second four-way valve (13) is configured such that it isswitchable between (i) a first state (see solid line representation inthe figure) that allows fluid communication between the first port (P1)and the second port (P2), and between the third port (P3) and the fourthport (P4) and (ii) a second state (see broken line representation in thefigure) that allows fluid communication between the first port (P1) andthe third port (P3), and between the second port (P2) and the fourthport (P4).

One end of an outdoor liquid pipe (heat source-side liquid pipe) (62)which is a liquid line is connected to the liquid-side end of theoutdoor heat exchanger (15). A receiver (17) for storing therein liquidrefrigerant is disposed along the outdoor liquid pipe (62), and theother end of the outdoor liquid pipe (62) is connected to the integratedliquid pipe (53) of the liquid-side interunit piping line (53, 54, 55).

The receiver (17) is connected to the outdoor liquid pipe (62) throughthese pipes: a first inflow pipe (63 a) which allows inflow ofrefrigerant from the outdoor heat exchanger (15), a first outflow pipe(63 b) which allows outflow of refrigerant to the liquid-side interunitpiping line (53, 54, 55), a second inflow pipe (liquid refrigerantinflow passageway) (63 c) which allows inflow of refrigerant from theliquid-side interunit piping line (53, 54, 55), and a second outflowpipe (63 d) which allows outflow of refrigerant to the outdoor heatexchanger (15).

A suction pipe (61 a) of the inverter compressor (11A) is connectedthrough a low pressure gas pipe (64) of the first system-side circuit(50A) to the low pressure gas-side interunit piping line (51). A suctionpipe (61 c) of the second non-inverter compressor (11C) is connectedthrough the first and second four-way valves (12, 13) to a low pressuregas pipe (either the outdoor second gas pipe (58 b) or the outdoor firstgas pipe (58 a)) of the second system-side circuit (50B). In addition, asuction pipe (61 b) of the first non-inverter compressor (11B) isconnected through the third four-way valve (14) to the suction pipe (61a) of the inverter compressor (11A) and to the suction pipe (61 c) ofthe second non-inverter compressor (11C).

More specifically, a branch pipe (61 d) is connected to the suction pipe(61 a) of the inverter compressor (11A) and a branch pipe (61 e) isconnected to the suction pipe (61 c) of the second non-invertercompressor (11C). And the branch pipe (61 d) of the suction pipe (61 a)of the inverter compressor (11A) is connected through a check valve(CV3) to the first port (P1) of the third four-way valve (14); thesuction pipe (61 b) of the first non-inverter compressor (11B) isconnected to the second port (P2) of the third four-way valve (14); andthe branch pipe (61 e) of the suction pipe (61 c) of the secondnon-inverter compressor (11C) is connected through a check valve (CV4)to the third port (P3) of the third four-way valve (14). The checkvalves (CV3, CV4) disposed respectively in the branch pipes (61 d, 61 e)permit only flow of refrigerant in the direction of the third four-wayvalve (14) while stopping reverse refrigerant flow. In addition, a highpressure introduction pipe (not shown) for introduction of the highpressure of the refrigerant circuit (50) is connected to the fourth port(P4) of the third four-way valve (14).

The third four-way valve (14) is configured such that it is switchablebetween (i) a first state (see solid line representation in the figure)that allows fluid communication between the first port (P1) and thesecond port (P2), and between the third port (P3) and the fourth port(P4) and (ii) a second state (see broken line representation in thefigure) that allows fluid communication between the first port (P1) andthe fourth port (P4), and between the second port (P2) and the thirdport (P3).

The first and second gas-side interunit piping lines (51, 52), and theintegrated liquid pipe (53) of the liquid-side interunit piping line(53, 54, 55) are extended outside from the outdoor unit (10), and theirassociated stop valves (18 a, 18 b, 18 c) are disposed within theoutdoor unit (10).

Connected to the outdoor liquid pipe (62) is an auxiliary liquid pipe(65) (the second outflow pipe (63 d)) which bypasses the receiver (17).Refrigerant flows through the auxiliary liquid pipe (65), mainly duringthe heating operation mode. The auxiliary liquid pipe (65) is providedwith an outdoor expansion valve (19) which is an expansion mechanism. Acheck valve (CV5) which permits only flow of refrigerant in thedirection of the receiver (17) is disposed between the outdoor heatexchanger (15) and the receiver (17) in the outdoor liquid pipe (62), inother words the check valve (CV5) is disposed in the first inflow pipe(63 a). The check valve (CV5) is positioned between a part of connectionwith the auxiliary liquid pipe (65) and the receiver (17) in the outdoorliquid pipe (62).

The outdoor liquid pipe (62) is diverged between the check valve (CV5)and the receiver (17) into a liquid branch pipe (66) (the second inflowpipe (63 c)), and is connected to between the stop valve (18 c) and acheck valve (CV7) (to be described later) in the outdoor liquid pipe(62). The liquid branch pipe (66) is provided with a check valve (CV6)which permits flow of refrigerant towards the receiver (17) from a pointof connection with the outdoor liquid pipe (62) between the stop valve(18 c) and the check valve (CV7).

The liquid branch pipe (66) (the second inflow pipe (63 c)) is a liquidrefrigerant inflow passageway which is connected to the outdoor liquidpipe (62) which is connected to the integrated liquid pipe (53) of theliquid-side interunit piping line (53, 54, 55), and to the inlet port ofthe receiver (17). The liquid refrigerant inflow passageway (66) isprovided with a solenoid valve (switch valve) (SV1) capable of beingon-off controlled. The solenoid valve (SV1) is disposed between a pointof connection with the outdoor liquid pipe (62) in the liquid branchpipe (66) and the check valve (CV6).

The outdoor liquid pipe (62) is provided, between a point of connectionwith the auxiliary liquid pipe (65) and the stop valve (18 c), with thecheck valve (CV7), in other words the check valve (CV7) is disposed inthe first outflow pipe (63 b). The check valve (CV7) permits only flowof refrigerant towards the stop valve (18 c) from the receiver (17).

A liquid injection pipe (67) is connected to the liquid branch pipe (66)(the second inflow pipe (63 c)) and to the low pressure gas pipe (64).One end of the liquid injection pipe (67) is connected between a pointof connection with the outdoor liquid pipe (62) and the solenoid valve(SV1) to the liquid branch pipe (66) (the second inflow pipe (63 c)). Inaddition, the other end of the liquid injection pipe (67) is connectedbetween the suction pipe (61 a) of the inverter compressor (11A) and thestop valve (18 a) to the low pressure gas pipe (64). The liquidinjection pipe (67) is provided with a motor-operated expansion valve(67 a) for flow rate control.

Indoor Unit

The indoor unit (20) is provided with an indoor heat exchanger (airconditioning heat exchanger) (21) which is a second utilization-sideheat exchanger and an indoor expansion valve (22) which is an expansionmechanism. The second gas-side interunit piping line (52) is connectedto the gas side of the indoor heat exchanger (21). On the other hand,the second branch liquid pipe (55) of the liquid-side interunit pipingline (53, 54, 55) is connected through the indoor expansion valve (22)to the liquid side of the indoor heat exchanger (21). Also note that theindoor heat exchanger (21) is, for example, a fin and tube heatexchanger of the cross fin type, and an indoor fan (23) which is autilization-side fan is disposed in vicinity to the indoor heatexchanger (21). In addition, the indoor expansion valve (22) is formedby a motor-operated expansion valve.

Cold Storage Unit

The cold storage unit (30) is provided with a cold storage heatexchanger (31) which is a first utilization-side heat exchanger(evaporator) and a cold storage expansion valve (32) which is anexpansion mechanism. The first branch liquid pipe (54) (the coldstorage-side first branch liquid pipe (54 a)) of the liquid-sideinterunit piping line (53, 54, 55) is connected through the cold storageexpansion valve (32) and then through a solenoid valve (SV2) to theliquid side of the cold storage heat exchanger (31). The solenoid valve(SV2) is employed to stop flow of refrigerant during the thermo-off(rest) operation mode. On the other hand, a cold storage-side branch gaspipe (51 a) diverged from the first gas-side interunit piping line (51)is connected to the gas side of the cold storage heat exchanger (31).

The cold storage heat exchanger (31) is in fluid communication with thesuction side of the inverter compressor (11A) while on the other handthe indoor heat exchanger (21) is in fluid communication with thesuction side of the second non-inverter compressor (11C) during thecooling operation mode. The refrigerant pressure (evaporation pressure)of the cold storage heat exchanger (31) is lower than the refrigerantpressure (evaporation pressure) of the indoor heat exchanger (21). Morespecifically, the refrigerant evaporation temperature of the coldstorage heat exchanger (31) is, for example, minus 10 degrees Centigradeand the refrigerant evaporation temperature of the indoor heat exchanger(21) is, for example, plus 5 degrees Centigrade, and the refrigerantcircuit (50) constitutes a circuit in which refrigerant is evaporated atdifferent temperatures.

Also note that the cold storage expansion valve (32) is atemperature-sensitive expansion valve and its temperature sensing bulbis mounted at the gas side of the cold storage heat exchanger (31).Accordingly, the degree of opening of the cold storage expansion valve(32) is controlled based on the temperature of refrigerant at the outletside of the cold storage heat exchanger (31). The cold storage heatexchanger (31) is, for example, a fin and tube heat exchanger of thecross fin type, and a cold storage fan (33) which is a cooling fan isdisposed in vicinity to the cold storage heat exchanger (31).

Freeze Storage Unit

The freeze storage unit (40) is provided with a freeze storage heatexchanger (41) which is a first utilization-side heat exchanger, afreeze storage expansion valve (42) which is an expansion mechanism, anda booster compressor (43) which is a freeze storage compressor. Thefirst branch liquid pipe (54) (the freeze storage-side first branchliquid pipe (54 b)) of the liquid-side interunit piping line (53, 54,55) is connected through the freeze storage expansion valve (42) andthen through the solenoid valve (SV3) to the liquid side of the freezestorage heat exchanger (41).

The gas side of the freeze storage heat exchanger (41) and the suctionside of the booster compressor (43) are connected together by aconnection gas pipe (68). Connected to the discharge side of the boostercompressor (43) is the freeze storage-side branch gas pipe (51 b)diverged from the first gas-side interunit piping line (51). The freezestorage-side branch gas pipe (51 b) is provided with a check valve (CV8)and an oil separator (44). Connected to between the oil separator (44)and the connection gas pipe (68) is an oil return pipe (69) having acapillary tube (45).

In order that the refrigerant evaporation temperature of the freezestorage heat exchanger (41) may fall below the refrigerant evaporationtemperature of the cold storage heat exchanger (31), the boostercompressor (43) performs, together with the compression mechanism (11D)of the first system, two-stage compression of refrigerant. It is setsuch that the refrigerant evaporation temperature of the freeze storageheat exchanger (41) is, for example, minus 35 degrees Centigrade.

Also note that the freeze storage expansion valve (42) is atemperature-sensitive expansion valve and its temperature sensing bulbis mounted at the gas side of the freeze storage heat exchanger (41).The freeze storage heat exchanger (41) is, for example, a fin and tubeheat exchanger of the cross fin type, and a freeze storage fan (46)which is a cooling fan is disposed in vicinity to the freeze storageheat exchanger (41).

In addition, a bypass pipe (70) having a check valve (CV9) is connectedto the connection gas pipe (68) which is the suction side of the boostercompressor (43), and to between the oil separator (44) and the checkvalve (CV8) in the freeze storage-side branch gas pipe (51 b). Thebypass pipe (70) is configured such that refrigerant is allowed to flow,bypassing the booster compressor (43) during the shutdown time (forexample, when the booster compressor (43) fails to operate properly).

Control System

The refrigerant circuit (50) is provided with various sensors andvarious switches. The high pressure gas pipe (57) of the outdoor unit(10) is provided with a high pressure sensor (75) which is a pressuredetector means for detection of the pressure of high pressurerefrigerant, and a discharge temperature sensor (76) which is atemperature detector means for detection of the temperature of highpressure refrigerant. The discharge pipe (56 c) of the secondnon-inverter compressor (11C) is provided with a discharge temperaturesensor (77) which is a temperature detector means for detection of thetemperature of high pressure refrigerant. In addition, the dischargepipe (56 a) of the inverter compressor (11A), the discharge pipe (56 b)of the first non-inverter compressor (11B), and the discharge pipe (56c) of the second non-inverter compressor (11C) are each provided with arespective pressure switch (78) for high pressure protection which isplaced in the opened state to stop its associated one of the compressors(11A, 11B, 11C) whenever the pressure of high pressure refrigerantreaches a predetermined value.

The suction pipe (61 a) of the inverter compressor (11A) is providedwith a low pressure sensor (79) which is a pressure detector means fordetection of the pressure of low pressure refrigerant, and a suctiontemperature sensor (81) which is a temperature detector means fordetection of the temperature of low pressure refrigerant. Likewise, thesuction pipe (61 c) of the second non-inverter compressor (11C) isprovided with a low pressure sensor (80) and a suction temperaturesensor (82).

The outdoor heat exchanger (15) is provided with an outdoor heatexchange sensor (83) which is a temperature detector means for detectionof the temperature of evaporation or condensation which is thetemperature of refrigerant in the outdoor heat exchanger (15). Inaddition, the outdoor unit (10) is provided with an outside airtemperature sensor (84) which is a temperature detector means fordetection of the temperature of outdoor air.

The indoor heat exchanger (21) is provided with an indoor heat exchangesensor (85) which is a temperature detector means for detection of thetemperature of evaporation or condensation which is the temperature ofrefrigerant in the indoor heat exchanger (21). The indoor heat exchanger(21) is also provided, at its gas side, with a gas temperature sensor(86) which is a temperature detector means for detection of thetemperature of gas refrigerant. In addition, the indoor unit (20) isprovided with a room temperature sensor (87) which is a temperaturedetector means for detection of the temperature of indoor air.

The cold storage unit (30) is provided with a cold storage temperaturesensor (88) which is a temperature detector means for detection of thecompartment temperature of the cold storage showcase. The freeze storageunit (40) is provided with a freeze storage temperature sensor (89)which is a temperature detector means for detection of the compartmenttemperature of the freeze storage showcase. In addition, the boostercompressor (43) has, at its discharge side, a pressure switch (90) forhigh pressure protection which is placed in the opened state to stop thebooster compressor (43) whenever the pressure of discharge refrigerantreaches a predetermined value.

Output signals from these various sensors and switches are fed to acontroller (control means) (95). The controller (95) is configured suchthat it controls the operation of the refrigerant circuit (50) wherebythe refrigerant circuit (50) is operated selectively in either one ofeight different operation modes (to be described later). And, inoperation, the controller (95) provides: control of the start, stop, andcapacity of the inverter compressor (11A); control of the start and stopof the first and second non-inverter compressors (11B, 11C); and controlof the adjustment of the degree of opening of the outdoor and indoorexpansion valves (19, 22). In addition, the controller (95) providescontrol of the switching of each of the four-way valves (12, 13, 14) andcontrol of the degree of opening of the motor-operated expansion valve(67 a) of the liquid injection pipe (67).

The controller (95) provides also control of the on-off of the solenoidvalve (SV1) of the liquid branch pipe (66) which is a liquid refrigerantinflow passageway in response to the operation state. More specifically,the controller (95) provides the following control when performing,without the use of the outdoor heat exchanger (15), a heating operationmode of 100% heat recovery in which the indoor heat exchanger (21)functions as a condenser and the cold and freeze storage heat exchangers(31, 42) function as evaporators.

In the first place, during the 100% heat recovery heating operationmode, the controller (95) performs the following control on the solenoidvalve (SV1). That is, when the discharge pressure of the compressionmechanism (11D, 11E) is below a predetermined value, the solenoid valve(SV1) is placed in the closed state. On the other hand, when thedischarge pressure of the compression mechanism (11D, 11E) increases toequal or exceed the predetermined value, the solenoid valve (SV1) isplaced in the opened state. In addition, during the 100% heat recoveryheating operation mode, the controller (95) further performs thefollowing control on the solenoid valve (SV1). That is, when the amountof liquid refrigerant accumulated in the indoor heat exchanger (21) andthe liquid-side interunit piping line (53, 54, 55) is below apredetermined value, the solenoid valve (SV1) is placed in the closedstate. On the other hand, when it is estimated that the liquidrefrigerant amount accumulated reaches the predetermined value or above,the solenoid valve (SV1) is placed in the opened state. Furthermore,during the 100% heat recovery heating operation mode, the controller(95) provides the following control on the solenoid valve (SV1). Thatis, when the temperature of liquid refrigerant in the indoor heatexchanger (21) is below a predetermined value, the solenoid valve (SV1)is placed in the closed state. On the other hand, when the liquidrefrigerant temperature increases to equal or exceed the predeterminedvalue, the solenoid valve (SV1) is placed in the opened state. Besides,during the 100% heat recovery heating operation mode, the controller(95) performs the following control on the solenoid valve (SV1). Thatis, when the pressure of liquid refrigerant in the liquid-side interunitpiping line (53, 54, 55) is below a predetermined value, the solenoidvalve (SV1) is placed in the closed state. On the other hand, when theliquid refrigerant pressure increases to equal or exceed thepredetermined value, the solenoid valve (SV1) is placed in the openedstate.

Also note that during the cooling operation mode (to be described later)and when the compression mechanism (11D, 11E) is placed at rest, thecontroller (95) provides control so that the solenoid valve (SV1) isplaced in the closed state. In addition, during the heating operationmode in which the outdoor heat exchanger (15) is used as an evaporator,the controller (95) provides control so that the solenoid valve (SV1) isplaced in the opened state.

Running Operation

Next, description will be made regarding each of operation modes of therunning operation of the refrigeration apparatus (1). The refrigerationapparatus (1) is configured such that it is selectively settable tooperate in either one of, for example, eight different operation modes,in the present embodiment. More specifically, the refrigerationapparatus (1) is so configured as to be able to selectively perform:

(i) a cooling operation mode that provides only indoor space cooling bythe indoor unit (20);(ii) a refrigeration operation mode that provides only compartmentcooling by the cold and freeze storage units (30, 40);(iii) a first cooling/refrigeration operation mode that provides indoorspace cooling by the indoor unit (20) simultaneously with compartmentcooling by the cold and freeze storage units (30, 40);(iv) a second cooling/refrigeration operation mode that is performed ifthe cooling capacity of the indoor unit (20) is insufficient in thefirst cooling/refrigeration operation mode;(v) a heating operation mode that provides only indoor space heating bythe indoor unit (20);(vi) a first heating/refrigeration operation mode that provides, withoutthe use of the outdoor heat exchanger (15), indoor space heating by theindoor unit (20) and compartment cooling by the cold and freeze storageunits (30, 40) with 100% heat recovery;(vii) a second heating/refrigeration operation mode that is performed ifthe heating capacity of the indoor unit (20) is in surplus in the firstheating/refrigeration operation mode; or(viii) a third heating/refrigeration operation mode that is performed ifthe heating capacity of the indoor unit (20) is insufficient in thefirst heating/refrigeration operation mode.

In the following, each of the above operation modes is described morespecifically.

Cooling Operation Mode

The cooling operation mode is an operation mode that provides onlyindoor space cooling by the indoor unit (20). During the coolingoperation mode, the inverter compressor (11A) alone constitutes thecompression mechanism (11D) of the first system while the firstnon-inverter compressor (11B) and the second non-inverter compressor(11C) together constitute the compression mechanism (11E) of the secondsystem, as shown in FIG. 2. And, only the first and second non-invertercompressors (11B, 11C), i.e., the compression mechanism (11E) of thesecond system, are activated.

In addition, as indicated by solid line representation in FIG. 2, thefirst and second four-way valves (12, 13) each change state to the firststate while, on the other hand, the third four-way valve (14) changesstates to the second state. In addition, the outdoor expansion valve(19), the motor-operated expansion valve (67 a) of the liquid injectionpipe (67), the solenoid valve (SV1) of the liquid branch pipe (66) (thesecond inflow pipe (63 c)) which is a liquid refrigerant inflowpassageway, the solenoid valve (SV2) of the cold storage unit (30), andthe solenoid valve (SV3) of the freeze storage unit (40) are all placedin the closed state.

In this state, discharged refrigerant from the first and secondnon-inverter compressors (11B, 11C) flows through the first four-wayvalve (12) and then through the outdoor first gas pipe (58 a) into theoutdoor heat exchanger (15), and is condensed to liquid refrigerant. Thecondensed liquid refrigerant flows through the outdoor liquid pipe (62),passes through the receiver (17), then through the integrated liquidpipe (53) of the liquid-side interunit piping line (53, 54, 55), andthen through the second branch liquid pipe (55), enters the indoor heatexchanger (21) by way of the indoor expansion valve (22), and isevaporated to gas refrigerant. The evaporated gas refrigerant passesthrough the second gas-side interunit piping line (52), then through theoutdoor second gas pipe (58 b), then through the first four-way valve(12), and then through the second four-way valve (13) and thereafterflows through the suction pipe (61 c) of the second non-invertercompressor (11C). A portion of this low pressure gas refrigerant isreturned back to the second non-inverter compressor (11C) while, on theother hand, the rest is diverged from the suction pipe (61 c) of thesecond non-inverter compressor (11C) to the branch pipe (61 e) and isretuned back to the first non-inverter compressor (11B) by way of thethird four-way valve (14). Repetition of such refrigerant circulationeffects cooling of the store space.

In this operation state, the start/stop of the first and secondnon-inverters (11B, 11C) and the degree of opening of the indoorexpansion valve (22) are controlled in response to the indoor coolingload. Only one of the compressors (11B, 11C) may be put in operation.

Refrigeration Operation Mode

The refrigeration operation mode is an operation mode that provides onlycompartment cooling by the cold and freeze storage units (30, 40).During the refrigeration operation mode, the inverter compressor (11A)and the first non-inverter compressor (11B) together constitute thecompression mechanism (11D) of the first system while, on the otherhand, the second non-inverter compressor (1C) alone constitutes thecompression mechanism (11E) of the second system, as shown in FIG. 3.And, the inverter compressor (11A) and the first non-inverter compressor(11B), i.e., the compression mechanism (11D) of the first system, areactivated together with the booster compressor (43), and the secondnon-inverter compressor (11C) is placed at rest.

In addition, as indicated by solid line representation in FIG. 3, thefirst and second four-way valves (12, 13) each change state to the firststate and the third four-way valve (14) also changes state to the firststate. Furthermore, the solenoid valve (SV2) of the cold storage unit(30) and the solenoid valve (SV3) of the freeze storage unit (40) areplaced in the opened state while, on the other hand, the solenoid valve(SV1) of the liquid branch pipe (66) (the second inflow pipe (63 c))which is a liquid refrigerant inflow passageway, the outdoor expansionvalve (19), and the indoor expansion valve (22) are placed in the closedstate. In addition, in response to the operation state, themotor-operated expansion valve (67 a) of the liquid injection pipe (67)is set either in the fully closed state or to a predetermined degree ofopening that allows liquid refrigerant to flow at a predetermined flowrate.

In this state, discharged refrigerant from the inverter and firstnon-inverter compressors (11A, 11B) flows through the first four-wayvalve (12) and then through the outdoor first gas pipe (58 a) into theoutdoor heat exchanger (15), and is condensed to liquid refrigerant. Thecondensed liquid refrigerant flows through the outdoor liquid pipe (62),passes through the receiver (17), and is diverged from the integratedliquid pipe (53) of the liquid-side interunit piping line (53, 54, 55)into the cold storage-side first branch liquid pipe (54 a) and into thefreeze storage-side first branch liquid pipe (54 b).

Liquid refrigerant flowing through the cold storage-side first branchliquid pipe (54 a) flows through the cold storage expansion valve (32)into the cold storage heat exchanger (31), is evaporated to gasrefrigerant, and then flows through the cold storage-side branch gaspipe (51 a). On the other hand, liquid refrigerant flowing through thefreeze storage-side first branch liquid pipe (54 b) flows through thefreeze storage expansion valve (42) into the freeze storage heatexchanger (41), is evaporated to gas refrigerant. The gas refrigerantevaporated in the freeze storage heat exchanger (41) is drawn into andcompressed in the booster compressor (43), and discharged to the freezestorage-side branch gas pipe (51 b).

The flow of the gas refrigerant evaporated in the cold storage heatexchanger (31) and the flow of the gas refrigerant discharged from thebooster compressor (43) join together in the first gas-side interunitpiping line (51). The combined refrigerant is then returned back throughthe low pressure gas pipe (64) to the inverter compressor (11A) and thefirst non-inverter compressor (11B). Repetition of such refrigerantcirculation effects cooling of the cold storage showcase compartment andcooling of the freeze storage showcase compartment.

The pressure of refrigerant in the freeze storage heat exchanger (41)falls below the pressure of refrigerant in the cold storage heatexchanger (31) since the refrigerant is sucked into the boostercompressor (43). As a result, for example, the temperature (evaporationtemperature) of refrigerant in the freeze storage heat exchanger (41) isminus 35 degrees Centigrade while, on the other hand, the temperature(evaporation temperature) of refrigerant in the cold storage heatexchanger (31) is minus 10 degrees Centigrade.

During the refrigeration operation mode, the start/stop of the firstnon-inverter compressor (11B) and either the start/stop or the capacityof the inverter compressor (11A) are controlled, for example, based onLP (the pressure of low pressure refrigerant) detected by the lowpressure sensor (79), whereby the refrigeration apparatus (1) operatesin response to the refrigeration load.

For example, when effecting control of increasing the capacity of thecompression mechanism (2D), the inverter compressor (11A) is firstactivated, with the first non-inverter compressor (11B) placed at rest.If, after the capacity of the inverter compressor (11A) increases to amaximum, there is a further increase in the load, then the capacity ofthe inverter compressor (1A) is decreased to a minimum simultaneouslywith activation of the first non-inverter compressor (11B). Thereafter,if the load increases still further, the capacity of the invertercompressor (11A) is increased while the first non-inverter compressor(11B) still remains activated. On the other hand, when effecting controlof reducing the compressor capacity, the opposite operation to thecompressor capacity increasing control is carried out.

The degree of opening of the cold storage and freeze storage expansionvalves (32, 42) is superheat controlled by their temperature-sensingbulbs. This is the same as in each of the following operation modes.

First Cooling/Refrigeration Operation Mode

The first cooling/refrigeration operation mode is an operation mode thatprovides indoor space cooling by the indoor unit (20) simultaneouslywith compartment cooling by the cold and freeze storage units (30, 40).As shown in FIG. 4, during the first cooling/refrigeration operationmode, the inverter compressor (11A) and the first non-invertercompressor (11B) together constitute the compression mechanism (11D) ofthe first system while, on the other hand, the second non-invertercompressor (11C) alone constitutes the compression mechanism (11E) ofthe second system. And, the inverter compressor (11A), the firstnon-inverter compressor (11B), and the second non-inverter compressor(11C) are all activated and, in addition, the booster compressor (43) isalso activated.

In addition, as indicated by solid line representation in FIG. 4, thefirst four-way valve (12), the second four-way valve (13), and the thirdfour-way valve (14) each change state to the first state. Further, thesolenoid valve (SV2) of the cold storage unit (30) and the solenoidvalve (SV3) of the freeze storage unit (40) are placed in the openedstate while, on the other hand, the solenoid valve (SV1) of the liquidbranch pipe (66) (the second inflow pipe (63 c)) which is a liquidrefrigerant inflow passageway and the outdoor expansion valve (19) areplaced in the closed state. In addition, in response to the operationstate, the motor-operated expansion valve (67 a) of the liquid injectionpipe (67) is set either in the fully closed state or to a predetermineddegree of opening that allows liquid refrigerant to flow to the suctionside of the compression mechanism (11D) at a predetermined flow rate.

In this state, the flow of discharged refrigerant from the invertercompressor (11A), the flow of discharged refrigerant from the firstnon-inverter compressor (11B), and the flow of discharged refrigerantfrom the second non-inverter compressor (11C) join together in the highpressure gas pipe (57). Thereafter, the combined refrigerant flowsthrough the first four-way valve (12) and then through the outdoor firstgas pipe (58 a) into the outdoor heat exchanger (15), and is condensedto liquid refrigerant. The condensed liquid refrigerant flows throughthe outdoor liquid pipe (62), passes through the receiver (17), andflows through the integrated liquid pipe (53) of the liquid-sideinterunit piping line (53, 54, 55).

A portion of the liquid refrigerant flowing through the integratedliquid pipe (53) of the liquid-side interunit piping line (53, 54, 55)diverges therefrom into the second branch liquid pipe (55), flowsthrough the indoor expansion valve (22) into the indoor heat exchanger(21), and is evaporated to gas refrigerant. The evaporated gasrefrigerant passes through the second gas-side interunit piping line(52), then through the outdoor second gas pipe (58 b), then through thefirst four-way valve (12), then through the second four-way valve (13),and then through the suction pipe (61 c), and is returned back to thesecond non-inverter compressor (11C).

On the other hand, the other portion of the liquid refrigerant flowingthrough the integrated liquid pipe (53) of the liquid-side interunitpiping line (53, 54, 55) diverges therefrom into the cold storage-sidefirst branch liquid pipe (54 a) and into the freeze storage-side firstbranch liquid pipe (54 b). The liquid refrigerant flowing through thecold storage-side first branch liquid pipe (54 a) flows through the coldstorage expansion valve (32) into the cold storage heat exchanger (31),is evaporated to gas refrigerant, and flows through the coldstorage-side branch gas pipe (51 a). Meanwhile, the liquid refrigerantflowing through the freeze storage-side first branch liquid pipe (54 b)flows through the freeze storage expansion valve (42) into the freezestorage heat exchanger (41), and is evaporated to gas refrigerant. Thegas refrigerant evaporated in the freeze storage heat exchanger (41) isdrawn into and compressed by the booster compressor (43) and thendischarged to the freeze storage-side branch gas pipe (51 b).

The flow of the gas refrigerant evaporated in the cold storage heatexchanger (31) and the flow of the gas refrigerant discharged from thebooster compressor (43) join together in the first gas-side interunitpiping line (51). Thereafter, the combined gas refrigerant is returnedback through the low pressure gas pipe (64) to the inverter compressor(11A) and the first non-inverter compressor (11B).

Repetition of such refrigerant circulation effects cooling of the storespace simultaneously with cooling of the cold storage showcasecompartment and cooling of the freeze storage showcase compartment.

Second Cooling/Refrigeration Operation Mode

The second cooling/refrigeration operation mode is an operation modethat is performed if the cooling capacity of the indoor unit (20) isinsufficient in the first cooling/refrigeration operation mode. In thesecond cooling/refrigeration operation mode, the first non-invertercompressor (11B) is switched to the air conditioning side. As shown inFIG. 5, the setting in the second cooling/refrigeration operation modeis basically the same as that in the first cooling/refrigerationoperation mode, with the exception that the third four-way valve (14)changes state to the second state.

Accordingly, during the second cooling/refrigeration operation mode,discharged refrigerant from the inverter compressor (11A), the firstnon-inverter compressor (11B), and the second non-inverter compressor(11C) is condensed in the outdoor, heat exchanger (15) and evaporated inthe indoor heat exchanger (21), the cold storage heat exchanger (31),and the freeze storage heat exchanger (41), in the same way as the firstcooling/refrigeration operation mode.

Then, the refrigerant evaporated in the indoor heat exchanger (21) isreturned back to the first and second non-inverter compressors (11B,11C) while, on the other hand, the refrigerant evaporated in the coldstorage heat exchanger (31) and the freeze storage heat exchanger (41)is returned back to the inverter compressor (11A). By use of these twocompressors (11B, 11C) on the air conditioning side, the lack of coolingcapacity is compensated.

Heating Operation Mode

The heating operation mode is an operation mode that provides onlyindoor space heating by the indoor unit (20). During the heatingoperation mode, the inverter compressor (11A) alone constitutes thecompression mechanism (11D) of the first system while, on the otherhand, the first and second non-inverter compressors (11B, 11C) togetherconstitute the compression mechanism (11E) of the second system, asshown in FIG. 6. And, only the first and second non-inverter compressors(11B, 11C), i.e., the compression mechanism (11E) of the second system,are activated.

Further, as indicated by solid line representation in FIG. 6, the firstfour-way valve (12) changes state to the second state; the secondfour-way valve (13) changes state to the first state; and the thirdfour-way valve (14) changes state to the second state. On the otherhand, the motor-operated expansion valve (67 a) of the liquid injectionpipe (67), the solenoid valve (SV2) of the cold storage unit (30), andthe solenoid valve (SV3) of the freeze storage unit (40) are all placedin the closed state. Furthermore, the indoor expansion valve (22) isfully opened; the solenoid valve (SV1) of the liquid branch pipe (66)(the second inflow pipe (63 c)) which is a liquid refrigerant inflowpassageway is opened; and the outdoor expansion valve (19) is controlledto a predetermined degree of opening.

In this state, discharged refrigerant from the first non-invertercompressor (11B) and the second non-inverter compressor (11C) flowsthrough the first four-way valve (12), then through the outdoor secondgas pipe (58 b), and then through the second gas-side interunit pipingline (52) into the indoor heat exchanger (21), and is condensed toliquid refrigerant. The condensed liquid refrigerant flows through thesecond branch liquid pipe (55) of the liquid-side interunit piping line(53, 54, 55) and then through the integrated liquid pipe (53) of theliquid-side interunit piping line (53, 54, 55), passes through theliquid branch pipe (66) (the second inflow pipe (63 c)) which is aliquid refrigerant inflow passageway, and flows into the receiver (17).Thereafter, the liquid refrigerant flows through the outdoor expansionvalve (19) of the auxiliary liquid pipe (65) into the outdoor heatexchanger (15), and is evaporated to gas refrigerant. The evaporated gasrefrigerant passes through the outdoor first gas pipe (58 a), thenthrough the first four-way valve (12), and then through the secondfour-way valve (13), flows through the suction pipe (61 c) of the secondnon-inverter compressor (1C), and is returned back to the first andsecond non-inverter compressors (11B, 11C). Repetition of suchrefrigerant circulation effects heating of the store space.

Only one of the compressors (11B, 11C) may be put in operation, as inthe cooling operation mode.

First Heating/Refrigeration Operation Mode

The first heating/refrigeration operation mode is a 100% heat recoveryoperation mode that provides space heating by the indoor unit (20) andcompartment cooling by the cold and freeze storage units (30, 40),without the use of the outdoor heat exchanger (15). In the firstheating/refrigeration operation mode, as shown in FIG. 7, the invertercompressor (11A) and the first non-inverter compressor (11B) togetherconstitute the compression mechanism (11D) of the first system while, onthe other hand, the second non-inverter compressor (11C) aloneconstitutes the compression mechanism (11E) of the second system. And,the inverter compressor (11A) and the first non-inverter compressor(11B) are activated, and the booster compressor (43) is also activated.The second non-inverter compressor (11C) is placed at rest.

Further, as indicated by solid line representation in FIG. 7, the firstfour-way valve (312) changes state to the second state while, on theother hand, the second and third four-way valves (13, 14) each changestate to the first state. Furthermore, the solenoid valve (SV2) of thecold storage unit (30) and the solenoid valve (SV3) of the freezestorage unit (40) are opened while, on the other hand, the outdoorexpansion valve (19) is closed. In addition, the solenoid valve (SV1) ofthe liquid branch pipe (66) (the second inflow pipe (63 c)) which is aliquid refrigerant inflow passageway is basically placed in the closedstate unless: the discharge pressure of the compression mechanism (11D)increases to equal or exceed a predetermined value; it is estimated thatthe amount of liquid refrigerant accumulated in the indoor heatexchanger (21) and the liquid-side interunit piping line (53, 54, 55)reaches a predetermined value or above; and the temperature of liquidrefrigerant in the indoor heat exchanger (21) increases to equal orexceed a predetermined value.

In this state, discharged refrigerant from the inverter compressor (11A)and the first non-inverter compressor (11B) flows through the firstfour-way valve (12), then through the outdoor second gas pipe (58 b),and then through the second gas-side interunit piping line (52) into theindoor heat exchanger (21), and is condensed to liquid refrigerant. Thecondensed liquid refrigerant is diverged, before the integrated liquidpipe (53), from the second branch liquid pipe (55) of the liquid-sideinterunit piping line (53, 54, 55) into the cold storage-side firstbranch liquid pipe (54 a) and into the freeze storage-side first branchliquid pipe (54 b).

The liquid refrigerant flowing through the cold storage-side firstbranch liquid pipe (54 a) flows through the cold storage expansion valve(32) into the cold storage heat exchanger (31), is evaporated to gasrefrigerant, and flows through the cold storage-side branch gas pipe (51a). Meanwhile, the liquid refrigerant flowing through the freezestorage-side first branch liquid pipe (54 b) flows through the freezestorage expansion valve (42) into the freeze storage heat exchanger(41), and is evaporated to gas refrigerant. The gas refrigerantevaporated in the freeze storage heat exchanger (41) is drawn into andcompressed in the booster compressor (43) and then discharged to thefreeze storage-side branch gas pipe (51 b).

The flow of the gas refrigerant evaporated in the cold storage heatexchanger (31) and the flow of the gas refrigerant discharged from thebooster compressor (43) join together in the first gas-side interunitpiping line (51). The combined refrigerant is then returned back throughthe low pressure gas pipe (64) to the inverter compressor (11A) and thefirst non-inverter compressor (11B). Repetition of such refrigerantcirculation effects heating of the store space simultaneously withcooling of the cold storage showcase compartment and cooling of thefreeze storage showcase compartment. During the firstheating/refrigeration operation mode, the cooling capacity (the amountof heat of evaporation) of the cold and freeze storage units (30, 40)and the heating capacity (the amount of heat of condensation) of theindoor unit (20) are in balance with each other whereby 100% heatrecovery is accomplished.

Also note that if the amount of liquid refrigerant flowing to the firstbranch liquid pipe (54) from the second branch liquid pipe (55) isinsufficient, liquid refrigerant is drawn into the first branch liquidpipe (54) from the receiver (17) by way of the integrated liquid pipe(53) of the liquid-side interunit piping line (53, 54, 55).

On the other hand, the pressure within the receiver (17) drops when thetemperature of outside air is low. Accordingly, if the solenoid valve(SV1) of the liquid branch pipe (66) as a liquid refrigerant inflowpassageway is not placed in the closed state, this may lead to theresult that the pressure of the integrated liquid pipe (53) of theliquid-side interunit piping line (53, 54, 55) also drops, and theliquid refrigerant condensed in the indoor heat exchanger (21) flowsneither into the cold storage heat exchanger (31) nor into the freezestorage heat exchanger (41) but enters the receiver (17) by way of theintegrated liquid pipe (53) from the second branch liquid pipe (55). Inthe present embodiment, however, it is possible to prevent inflow ofliquid refrigerant to the receiver (17) by placing the solenoid valve(SV1) of the liquid branch pipe (66) in the closed state. In otherwords, the pressure of the integrated liquid pipe (53) can be preventedfrom falling to a lower level by placing the solenoid valve (SV1) in theclosed state. This ensures that liquid refrigerant exiting the indoorheat exchanger (21) is introduced into the cold storage heat exchanger(31) and into the freeze storage heat exchanger (41). In addition, it isensured that the drop in capacity due to the insufficiency in the flowrate of liquid refrigerant in the cold and the freeze storage heatexchangers (31, 41) is prevented.

On the other hand, when one of the two indoor units (20) is placed inthe thermo-off state (which is a state that performs an air supplyoperation in which refrigerant either stops circulating through theindoor heat exchanger (21) or is allowed to flow therethrough, but invery small amount) during the 100% heat recovery operation, the indoorexpansion valve (22) connected to the indoor heat exchanger (21) iseither placed in the fully closed state or set to a very small degree ofopening even when opened. At this time, the other indoor unit (20) inoperation continuously provides space heating, and dischargedrefrigerant from the compression mechanism (11D) is supplied also to thethermo-offed indoor heat exchanger (21). However, in the thermo-offedindoor heat exchanger (21), little refrigerant flows, resulting ingradual accumulation of refrigerant therein.

If, at this time, there is a request that the cooling capacity of thecold and freeze storage heat exchangers (31, 41) be increased, anoperation to increase the capacity of the compression mechanism (11D) iscarried out. As a result, the discharge pressure of the compressionmechanism (11D) increases, and if the solenoid valve (SV1) of the liquidbranch pipe (66) remains closed, the discharge pressure increases toomuch. In the present invention, however, because of the operation toplace the solenoid valve (SV1) in the opened state, it becomes possibleto permit escape of the liquid refrigerant to the receiver (17) wherebythe discharge pressure of the compressor is prevented from increasingtoo much.

In addition, the following possibility exists in conventionalrefrigeration apparatus in which the liquid branch pipe (66) is providedwith a relief valve. That is, the discharge pressure of the compressionmechanism (11D) increases too much before the relief valve is opened,thereby activating the pressure switch (78) for high pressureprotection. As a result, the compression mechanism (11D) stopsoperating, thereby causing the apparatus to stop operating due tomalfunction. In the present embodiment, however, such malfunction isprevented by setting the set pressure, at which the solenoid valve (SV1)is placed in the opened state when the high pressure of the refrigerantcircuit (50) increase, to fall below the working pressure of thepressure switch (78).

In addition, during the 100% heat recover operation mode, the solenoidvalve (SV1) is controlled as follows. If the amount of liquidrefrigerant accumulated in the indoor heat exchanger (21) and theliquid-side interunit piping line (53, 54, 55) is below a predeterminedvalue, the solenoid valve (SV1) is closed. On the other hand, if it isestimated that the liquid refrigerant amount reaches the predeterminedvalue or above, the solenoid valve (SV1) is opened. In this case, if thevalue detected by the gas temperature sensor (86) for detection of thetemperature of gas refrigerant in the indoor heat exchanger (21)approaches the saturated temperature corresponding to the pressure, itcan be estimated that there is an accumulation of liquid refrigerant inthe indoor heat exchanger (21) and the liquid-side interunit piping line(53, 54, 55).

If, in the way as described above, it is estimated that the liquidrefrigerant amount reaches the predetermined value or above, then thesolenoid valve (SV1) is opened to thereby permit escape of high pressurerefrigerant in the indoor heat exchanger (21) and the liquid-sideinterunit piping line (53, 54, 55) into the receiver (17). Accordingly,even in the case where there is no/little increase in the dischargepressure of the compression mechanism (11D), it is possible to preventtoo much accumulation of liquid refrigerant in the indoor heat exchanger(21) and the liquid-side interunit piping line (53, 54, 55).

In addition, during the 100% heat recovery operation mode, the solenoidvalve (SV1) is controlled as follows. That is, if the temperature ofliquid refrigerant in the indoor heat exchanger (21) is below apredetermined value, the solenoid valve (SV1) is closed. On the otherhand, if the liquid refrigerant temperature increases to equal or exceedthe predetermined value, the solenoid valve (SV1) is opened. Also inthis case, by setting the pressure corresponding to the set temperatureat which the solenoid valve (SV1) is opened to fall below the workingpressure of the pressure switch (78) for high pressure protection, itbecomes possible to prevent the discharge pressure of the compressionmechanism (11D) from increasing too much.

Furthermore, during the 100% heat recovery operation mode, the solenoidvalve (SV1) is controlled as follows. That is, if the pressure of liquidrefrigerant in the liquid-side interunit piping line (53, 54, 55) isbelow a predetermined value, the solenoid valve (SV1) is closed. On theother hand, if the liquid refrigerant pressure increases to equal orexceed the predetermined value, the solenoid valve (SV1) is opened. Thereason for this is that since the heating capacity is sufficientlyobtained when the pressure of the liquid-side interunit piping line (53,54, 55) is high, it is necessary to permit escape of liquid refrigerantto the receiver (17).

More specifically, the following control is possible. In the firstplace, if, when it is estimated that the difference between thetemperature of gas refrigerant and the temperature of liquid refrigerantdetected respectively by the temperature sensors (86, 85) disposedrespectively at the inlet and outlet sides of the indoor heat exchanger(21)) is small during the heating operation mode of 100% heat recovery(which is an operation mode during which the indoor fan (23) isrotated), it is possible to estimate that: the gas refrigeranttemperature approaches the liquid refrigerant temperature; there is anaccumulation of liquid refrigerant in the indoor heat exchanger (21);and the pressure of the liquid-side interunit piping line (53, 54, 55)is high. Accordingly, the solenoid valve (SV1) is controlled such thatit enters the opened state.

In the second place, since the high pressure tends to increase when theroom temperature approaches a set temperature (i.e., when being about tobe thermo-offed) or when an overload occurs because the room temperatureis high, the solenoid valve (SV1) is controlled such that it enters theopened state. In addition, since the room temperature is assumed to behigh when the temperature of outside air is high, the solenoid valve(SV1) is likewise controlled such that it enters the opened state.

By virtue of the above-described arrangement, it becomes possible toprevent the discharge pressure of the compression mechanism (11D) fromincreasing too much.

Second Heating/Refrigeration Operation Mode

The second heating/refrigeration operation mode is an operation modethat is performed when the heating capability of the indoor unit (20) ismore than needed in the first heating/refrigeration operation mode.During the second heating/refrigeration operation mode, as shown in FIG.8, the inverter compressor (11A) and the first non-inverter compressor(11B) together constitute the compression mechanism (11D) of the firstsystem while on the other hand the second non-inverter compressor (11C)alone constitutes the compression mechanism (11E) of the second system.And the inverter compressor (11A) and the first non-inverter compressor(11B) are activated and, in addition, the booster compressor (43) isalso activated. The second non-inverter compressor (11C) is placed atrest.

The second heating/refrigeration operation mode is similar to the firstheating/refrigeration operation mode (for example, the same valvesetting), with the exception that the second four-way valve (13) changesstate to the second state, as indicated by solid line representation inFIG. 8.

Accordingly, a portion of the discharged refrigerant from the invertercompressor (11A) and the first non-inverter compressor (11B) flows intothe indoor heat exchanger (21), and is condensed to liquid refrigerant,as in the first heating/refrigeration operation mode. The condensedliquid refrigerant flows, before the integrated liquid pipe (53), intothe first branch liquid pipe (54) (the cold storage-side first branchliquid pipe (54 a) and the freeze storage-side first branch liquid pipe(54 b)) from the second branch liquid pipe (55) of the liquid-sideinterunit piping line (53, 54, 55).

On the other hand, the other portion of the discharged refrigerant fromthe inverter compressor (11A) and the first non-inverter compressor(11B) passes through the auxiliary gas pipe (59), then through thesecond four-way valve (13), and then through the first four-way valve(12). Thereafter, the refrigerant flows through the outdoor first gaspipe (58 a), and is condensed to liquid refrigerant in the outdoor heatexchanger (15). The condensed liquid refrigerant passes through thereceiver (17) during flow through the outdoor liquid pipe (62), passesthrough the integrated liquid pipe (53) of the liquid-side interunitpiping line (53, 54, 55), flows to the first branch liquid pipe (54)(the cold storage-side first branch liquid pipe (54 a) and the freezestorage-side first branch liquid pipe (54 b)), and joins the refrigerantfrom the second branch liquid pipe (55).

Thereafter, the liquid refrigerant flowing through the cold storage-sidefirst branch liquid pipe (54 a) flows into the cold storage heatexchanger (31), is evaporated to gas refrigerant, and flows through thecold storage-side branch gas pipe (51 a). On the other hand, the liquidrefrigerant flowing through the freeze storage-side first branch liquidpipe (54 b) flows into the freeze storage heat exchanger (41), isevaporated to gas refrigerant, is drawn into and compressed in thebooster compressor (43), and is discharged to the freeze storage-sidebranch gas pipe (51 b). The flow of the gas refrigerant evaporated inthe cold storage heat exchanger (31) and the flow of the gas refrigerantdischarged from the booster compressor (43) join together in the firstgas-side interunit piping line (51). The combined refrigerant is thenreturned back, through the low pressure gas pipe (64), to the invertercompressor (11A) and the first non-inverter compressor (11B).

During the second heating/refrigeration operation mode, repetition ofsuch refrigerant circulation effects heating of the store spacesimultaneously with cooling of the cold storage showcase compartment andcooling of the freeze storage showcase compartment. At this time, thecooling capacity (the amount of heat of evaporation) of the cold andfreeze storage units (30, 40) and the heating capacity (the amount ofheat of condensation) of the indoor unit (20) are out of balance witheach other, and surplus heat of condensation is discharged to outsidethe room in the outdoor heat exchanger (15).

Third Heating/Refrigeration Operation Mode

The third heating/refrigeration operation mode is an operation mode thatis performed if the heating capability of the indoor unit (20) isinsufficient in the first heating/refrigeration operation mode. Duringthe third heating/refrigeration operation mode, as shown in FIG. 9, theinverter compressor (11A) and the first non-inverter compressor (11B)together constitute the compression mechanism (11D) of the first systemwhile, on the other hand, the second non-inverter compressor (11C) aloneconstitutes the compression mechanism (11E) of the second system. And,the inverter compressor (11A), the first non-inverter compressor (11B),and the second non-inverter compressor (11C) are activated and, inaddition, the booster compressor (43) is also activated.

The third heating/refrigeration operation mode is set in the same way asthe first heating/refrigeration operation mode, with the exception that:the degree of opening of the outdoor expansion valve (19) is controlled;the solenoid valve (SV1) of the liquid branch pipe (66) is opened; andthe second non-inverter compressor (11C) is activated.

Accordingly, discharged refrigerant from the inverter compressor (11A),the first non-inverter compressor (11B), and the second non-invertercompressor (11C) flows through the second gas-side interunit piping line(52) into the indoor heat exchanger (21), and is condensed to liquidrefrigerant, as in the first heating/refrigeration operation mode. Thecondensed liquid refrigerant diverges from the second branch liquid pipe(55) of the liquid-side interunit piping line (53, 54, 55) into thefirst branch liquid pipe (54) (the cold storage-side first branch liquidpipe (54 a) and the freeze storage-side first branch liquid pipe (54 b))and into the integrated liquid pipe (53).

The liquid refrigerant flowing through the cold storage-side firstbranch liquid pipe (54 a) flows into the cold storage heat exchanger(31), is evaporated to gas refrigerant, and flows through the coldstorage-side branch gas pipe (51 a). Meanwhile, the liquid refrigerantflowing through the freeze storage-side first branch liquid pipe (54 b)flows into the freeze storage heat exchanger (41), is evaporated to gasrefrigerant, is drawn into and compressed in the booster compressor(43), and is discharged to the freeze storage-side branch gas pipe (51b). The flow of the gas refrigerant evaporated in the cold storage heatexchanger (31) and the flow of the gas refrigerant discharged from thebooster compressor (43) join together in the first gas-side interunitpiping line (51). The combined refrigerant is then returned back,through the low pressure gas pipe (64), to the inverter compressor (11A)and to the first non-inverter compressor (11B).

On the other hand, the liquid refrigerant condensed in the indoor heatexchanger (21) and thereafter flowing through the integrated liquid pipe(53) flows through the liquid branch pipe (66) into the receiver (17).Thereafter, the liquid refrigerant flows into the outdoor heat exchanger(15) by way of the outdoor expansion valve (19) and is evaporated to gasrefrigerant. The evaporated gas refrigerant flows through the outdoorfirst gas pipe (58 a), then through the first four-way valve (12), andthen through the second four-way valve (13). Then, the gas refrigerantflows through the suction pipe (61 c) of the second non-invertercompressor (11C), and is returned back to the second non-invertercompressor (11C).

During the third heating/refrigeration operation mode, repetition ofsuch refrigerant circulation effects heating of the store spacesimultaneously with cooling of the cold storage showcase compartment andcooling of the freeze storage showcase compartment. At this time, thecooling capacity (the amount of heat of evaporation) of the cold andfreeze storage units (30, 40) and the heating capacity (the amount ofheat of condensation) of the indoor unit (20) are out of balance witheach other, and the amount of heat of evaporation lacked is obtainedfrom the outdoor heat exchanger (15).

Advantageous Effects of the Embodiment

In the present embodiment, during the 100% heat recovery operation modein which: the outdoor heat exchanger (15) is not used; the indoor heatexchanger (21) functions as a condenser; and the cold and freeze storageheat exchangers (31, 41) function as evaporators, the solenoid valve(SV1) of the liquid branch pipe (66) is placed in the closed state undernormal conditions whereby the apparatus is able to operate wherein thequantity of heat of condensation of the indoor heat exchanger (21) andthe quantity of heat of evaporation of the cold and freeze heatexchangers (31, 41) are in balance with each other.

On the other hand, for example, if the operation capacity of thecompression mechanism (11D) is increased when there is excessrefrigerant in the indoor heat exchanger (21) and the liquid-sideinterunit piping line (53, 54, 55), the solenoid valve (SV1) is placedin the opened state to thereby permit escape of the liquid refrigerantaccumulated in the indoor heat exchanger (21) and the liquid-sideinterunit piping line (53, 54, 55) to the receiver (17), and so itbecomes possible to prevent the high pressure of the compressionmechanism (11D) from increasing too much. Accordingly, if it is arrangedsuch that prior to activation of the pressure switch (78) for highpressure protection the solenoid valve (SV1) is placed in the openedstate, this makes it possible to prevent the refrigeration apparatusfrom malfunctioning to stop operating due to shutdown of the compressionmechanism (11D).

In addition, in the present embodiment, the two indoor units (20) areconnected in parallel. The discharge pressure of the compressionmechanism (11D) tends to increase due to accumulation of liquidrefrigerant in the indoor heat exchanger (21) and the liquid-sideinterunit piping line (53, 54, 55), when one of the two indoor units(20) is placed in the thermo-off state, and the apparatus tends to stopoperating due to activation of the pressure switch (78) for highpressure protection. However, the solenoid valve (SV1) is opened priorto activation of the pressure switch (78), thereby ensuring that themalfunction of the refrigeration apparatus is prevented from occurring.

In addition, it is possible to prevent the occurrence of problemconditions to the apparatus by closing the solenoid valve (SV1) duringthe cooling operation mode and opening the solenoid valve (SV1) onlywhen the outdoor heat exchanger (15) functions as an evaporator.

Another Embodiment

With respect to the above-described embodiment, the followingconfigurations may be employed.

For example, although the description has been made in regard to anexemplary case where two indoor units (20), eight cold storage units(30), and a freeze storage unit (40) are disposed to a single outdoorunit (10). However, the number of utilization-side units (20), thenumber of utilization-side units (30), and the number ofutilization-side units (40) may be modified according to need as long asthe 100% heat recovery operation mode is possible to perform.

In addition, in the above-described embodiment, the description has beenmade in regard to an exemplary case where the compression mechanism(11D, 11E) is formed by the three compressors (11A, 11B, 11C). However,the number of compressors may be modified according to need.

It should be noted that the above-described embodiments are essentiallypreferable exemplifications which are not intended in any sense to limitthe scope of the present invention, its application, or its applicationrange.

INDUSTRIAL APPLICABILITY

As has been described above, the present invention finds its utility inthe field of refrigeration apparatuses having multiple systems ofutilization-side heat exchangers and capable of performing a 100% heatrecovery operation mode between each utilization-side heat exchanger.

1. A refrigeration apparatus comprising: a heat source-side unit (10)including a compression mechanism (11D, 11E), a heat source-side heatexchanger (15), and a receiver (17); a first utilization-side unit (30,40) including a first utilization-side heat exchanger (31, 41); a secondutilization-side unit (20) including a second utilization-side heatexchanger (21); and a gas-side interunit piping line (51, 52) and aliquid-side interunit piping line (53, 54, 55) which establishconnections between each unit (10, 20, 30, 40) to thereby constitute arefrigerant circuit (50); the gas-side interunit piping line (51, 52)including: a first gas-side interunit piping line (51) which isconnected to the heat source-side unit (10) and to the firstutilization-side unit (30, 40); and a second gas-side interunit pipingline (52) which is connected to the heat source-side unit (10) and tothe second utilization-side unit (20); the liquid-side interunit pipingline (53, 54, 55) including: an integrated liquid pipe (53) which isconnected to the heat source-side unit (10); a first branch liquid pipe(54) which diverges from the integrated liquid pipe (53) to connect tothe first utilization-side unit (30, 40); and a second branch liquidpipe (55) which diverges from the integrated liquid pipe (53) to connectto the second utilization-side unit (20); wherein the refrigerationapparatus further comprises: a liquid refrigerant inflow passageway (66)which is connected to a heat source-side liquid pipe (62) of the heatsource-side unit (10), the heat source-side liquid pipe (62) beingconnected to the integrated liquid pipe (53) of the liquid-sideinterunit piping line (53, 54, 55), and to an inlet port of the receiver(17); and a switch valve (SV1) which is disposed in the liquidrefrigerant inflow passageway (66) and which is capable of being on-offcontrolled.
 2. The refrigeration apparatus of claim 1, wherein aplurality of the second utilization-side units (20) are connected inparallel to the heat source-side unit (10).
 3. The refrigerationapparatus of claim 1, wherein the first utilization-side unit (30, 40)is a cooling machine for providing compartment cooling and the heatsource-side unit (10) and the first utilization-side unit (30, 40)together constitute a first system-side circuit (50A) in whichrefrigerant is circulated in one direction; and wherein the secondutilization-side unit (20) is an air conditioning machine for providingindoor air conditioning and the heat source-side unit (10) and thesecond utilization-side unit (20) together constitute a secondsystem-side circuit (50B) in which refrigerant is reversibly circulated.4. The refrigeration apparatus of claim 1, wherein the refrigerationapparatus further comprises control means (95) for performing on-offcontrol of the switch valve (SV1) in response to the operation state. 5.The refrigeration apparatus of claim 4, wherein the control means (95)is configured such that in an operation state in which the secondutilization-side heat exchanger (21) functions as a condenser while thefirst utilization-side heat exchanger (31, 41) functions as anevaporator, the switch valve (SV1) is placed either in the closed stateif the discharge pressure of the compression mechanism (11D, 11E) isbelow a predetermined value or in the opened state if the dischargepressure of the compression mechanism (11D, 11E) increases to equal orexceed the predetermined value.
 6. The refrigeration apparatus of claim4, wherein the control means (95) is configured such that in anoperation state in which the second utilization-side heat exchanger (21)functions as a condenser while the first utilization-side heat exchanger(31, 41) functions as an evaporator, the switch valve (SV1) is placedeither in the closed state if the amount of liquid refrigerantaccumulated in the second utilization-side heat exchanger (21) and theliquid-side interunit piping line (53, 54, 55) is below a predeterminedvalue or in the opened state if it is estimated that the liquidrefrigerant amount accumulated reaches the predetermined value or above.7. The refrigeration apparatus of claim 4, wherein the control means(95) is configured such that in an operation state in which the secondutilization-side heat exchanger (21) functions as a condenser while thefirst utilization-side heat exchanger (31, 41) functions as anevaporator, the switch valve (SV1) is placed either in the closed stateif the temperature of liquid refrigerant in the second utilization-sideheat exchanger (21) is below a predetermined value or in the openedstate if the liquid refrigerant temperature increases to equal or exceedthe predetermined value.
 8. The refrigeration apparatus of claim 4,wherein the control means (95) is configured such that in an operationstate in which the second utilization-side heat exchanger (21) functionsas a condenser while the first utilization-side heat exchanger (31, 41)functions as an evaporator, the switch valve (SV1) is placed either inthe closed state if the pressure of liquid refrigerant in theliquid-side interunit piping line (53, 54, 55) is below a predeterminedvalue or in the opened state if the liquid refrigerant pressureincreases to equal or exceed the predetermined value.